Cascade refrigeration system with fluoroolefin refrigerant

ABSTRACT

The present invention relates to a cascade refrigeration system which circulates a refrigerant comprising a fluoroolefin therethrough. The cascade refrigeration system includes a low temperature refrigeration loop and a medium temperature refrigeration loop. The fluoroolefin circulates through either loop, or both. In a particular embodiment, the fluoroolefin circulates through the medium temperature loop. In a particular embodiment, where the cascade refrigeration system includes a first and a second cascade heat exchanger, and a secondary heat transfer loop which extends between the first and second cascade heat exchangers, either the first and/or second refrigerant may be, but need not necessarily be, a fluoroolefin.

BACKGROUND

1. Field of the Disclosure

The present disclosure relates to a cascade refrigeration system which circulates a refrigerant comprising a fluoroolefin therethrough. In particular, such a cascade system includes a medium temperature loop and a low temperature loop, and a fluoroolefin refrigerant may be used in either loop, or both.

2. Description of Related Art

Cascade refrigeration systems are known in the art, see for example, ICR07-B2-358, “CO₂-DX Systems for Medium-and Low-Temperature Refrigeration in Supermarket Applications”, T. Sienel, O. Finckh, International Congress of Refrigeration, 2007, Beijing. Such a system typically uses a refrigerant such as 1,1,1,2-tetrafluoroethane (R134a) or blends thereof with HFC-125 and HFC-143a (i.e., R404A) in the medium temperature loop and carbon dioxide (CO₂) in the low temperature loop to provide cooling to display cases, for instance, in supermarkets.

The refrigeration industry has been working for the past few decades to find replacement refrigerants for the ozone-depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) being phased out as a result of the Montreal Protocol. The solution for most refrigerant producers has been the commercialization of hydrofluorocarbon (HFC) refrigerants. The new HFC refrigerants, HFC-134a being the most widely used at this time, have zero ozone depletion potential and thus are not affected by the current regulatory phase out as a result of the Montreal Protocol.

Further environmental regulations may ultimately cause global phase out of certain HFC refrigerants. Currently, the automobile industry is facing regulations relating to global warming potential for refrigerants used in mobile air-conditioning. Therefore, there is a great current need to identify new refrigerants with reduced global warming potential for the mobile air-conditioning market. Should the regulations be more broadly applied in the future, for instance for stationary air conditioning and refrigeration systems, an even greater need will be felt for refrigerants that can be used in all areas of the refrigeration and air-conditioning industry.

Currently proposed replacement refrigerants for HFC-134a include HFC-152a, pure hydrocarbons such as butane or propane, or “natural” refrigerants such as CO₂. Many of these suggested replacements are toxic, flammable, and/or have low energy efficiency. New replacements are also being proposed for HCFC-22, R404A, R407C and R410A, among others. As these replacements are found, new uses of such alternative refrigerants are being sought in order to take advantage of their low or zero ozone depletion potential and lower global warming potential.

SUMMARY OF THE INVENTION

The object of the present disclosure is to provide cascade refrigeration systems which use refrigerant compositions which have unique characteristics to meet the demands of low or zero ozone depletion potential and lower global warming potential as compared to current refrigerants.

In addition to lower global warming potential advantages, the cascade refrigeration systems of the present invention may have higher energy efficiency and capacity than currently used cascade refrigeration systems.

Therefore, in accordance with the present invention there is provided a cascade refrigeration system having at least two refrigeration loops, each circulating a refrigerant therethrough, comprising:

-   -   (a) a first expansion device for reducing the pressure and         temperature of a first refrigerant liquid;     -   (b) an evaporator having an inlet and an outlet, wherein the         first refrigerant liquid from the first expansion device enters         the evaporator through the evaporator inlet and is evaporated in         the evaporator to form a first refrigerant vapor, thereby         producing cooling, and circulates to the outlet;     -   (c) a first compressor having an inlet and an outlet, wherein         the first refrigerant vapor from the evaporator circulates to         the inlet of the first compressor and is compressed, thereby         increasing the pressure and the temperature of the first         refrigerant vapor, and the compressed first refrigerant vapor         circulates to the outlet of the first compressor;     -   (d) a cascade heat exchanger system having:         -   (i) a first inlet and a first outlet, wherein the first             refrigerant vapor circulates from the first inlet to the             first outlet and is condensed in the heat exchanger system             to form a first refrigerant liquid, thereby rejecting heat,             and         -   (ii) a second inlet and a second outlet, wherein a second             refrigerant liquid circulates from the second inlet to the             second outlet and absorbs the heat rejected by the first             refrigerant and forms a second refrigerant vapor;     -   (e) a second compressor having an inlet and an outlet, wherein         the second refrigerant vapor from the cascade heat exchanger         system is drawn into the compressor and is compressed, thereby         increasing the pressure and temperature of the second         refrigerant vapor;     -   (f) a condenser having an inlet and an outlet for circulating         the second refrigerant vapor therethrough and for condensing the         second refrigerant vapor from the compressor to form a second         refrigerant liquid, wherein the second refrigerant liquid exits         the condenser through the condenser outlet; and     -   (g) a second expansion device which reduces the pressure and         temperature of the second refrigerant liquid exiting the         condenser and entering the second inlet of the cascade heat         exchanger system.

Either the first refrigerant or the second refrigerant, or both, may comprise a fluoroolefin.

In a particular embodiment, the cascade heat exchanger system may include a first and a second cascade heat exchanger, and a secondary heat transfer loop which extends between the first and the second cascade heat exchanger. In this embodiment, the second refrigerant liquid indirectly absorbs the heat rejected by the first refrigerant vapor through a heat transfer fluid which circulates between the first cascade heat exchanger and the second cascade heat exchanger through the secondary heat transfer loop. The first cascade heat exchanger has a first inlet and a first outlet, and a second inlet and a second outlet, wherein the first refrigerant vapor circulates from the first inlet to the first outlet and rejects heat and is condensed, and a secondary heat transfer fluid circulates from the second inlet to the second outlet and absorbs the heat rejected from the first refrigerant vapor and circulates to the second cascade heat exchanger. The second cascade heat exchanger has a first inlet and a first outlet, and a second inlet and a second outlet, wherein the heat transfer fluid circulates from the second outlet of the first cascade heat exchanger to the first inlet of the second cascade heat exchanger and to the first outlet of the second cascade heat exchanger and rejects the heat absorbed from the first refrigerant. The second refrigerant liquid circulates from the second inlet to the second outlet of the second cascade heat exchanger and absorbs the heat rejected by the heat transfer fluid and forms a second refrigerant vapor. In this embodiment, either the first and/or second refrigerant may be, but need not necessarily be, a fluoroolefin.

Further in accordance with the present invention, there is provided a method of exchanging heat between at least two refrigeration loops, comprising:

-   -   (a) absorbing heat from a body to be cooled in a first         refrigeration loop and rejecting this heat to a second         refrigeration loop; and     -   (b) absorbing the heat from the first refrigeration loop in the         second refrigeration loop and rejecting this heat to ambient,         wherein the refrigerant in at least one of the refrigeration         loops comprises a fluoroolefin.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be better understood with reference to the following Figures, wherein:

FIG. 1 is a schematic diagram of a cascade refrigeration system according to one embodiment of the present invention.

FIG. 2 is a schematic diagram of another embodiment of the cascade refrigeration system of the present invention.

FIG. 3 is a schematic diagram of a further embodiment of the present invention which shows a cascade refrigeration system with a secondary heat transfer loop which transfers heat from a lower temperature loop to a higher temperature loop.

FIG. 4 is a schematic diagram of yet another embodiment of the cascade refrigeration system of the present invention which has multiple low temperature loops.

FIG. 5 is a graph of the cooling capacity and COP for a refrigerant composition comprising HFO-1234yf and HFC-134a versus the weight percent of HFO-1234yf in the composition.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before addressing details of embodiments described below, some terms are defined or clarified.

Refrigeration capacity (also referred to as cooling capacity) is a term to define the change in enthalpy of a refrigerant in an evaporator per unit mass of refrigerant circulated, or the heat removed by the refrigerant in the evaporator per unit volume of refrigerant vapor exiting the evaporator (volumetric capacity). The refrigeration capacity is a measure of the ability of a refrigerant or heat transfer composition to produce cooling. Therefore, the higher the capacity, the greater the cooling that is produced for a given refrigerant circulation rate. Cooling rate refers to the heat removed by the refrigerant in the evaporator per unit time.

Coefficient of performance (COP) is the amount of heat removed from a body to be cooled divided by the required energy input to operate the cycle over a given time interval. The higher the COP, the higher is the energy efficiency. COP is directly related to the energy efficiency ratio (EER) that is the efficiency rating for refrigeration or air conditioning equipment at a specific set of internal and external temperatures.

Global warming potential (GWP) is an index for estimating relative global warming contribution due to atmospheric emission of a kilogram of a particular greenhouse gas compared to emission of a kilogram of carbon dioxide. GWP can be calculated for different time horizons showing the effect of atmospheric lifetime for a given gas. The GWP for the 100 year time horizon is commonly the value referenced. For mixtures, a mass-fraction weighted average can be calculated based on the individual GWPs for each component.

Ozone depletion potential (ODP) is a number that refers to the amount of stratospheric ozone depletion caused by a substance. The ODP is the ratio of the impact on stratospheric ozone of a chemical compared to the impact of a similar mass of CFC-11 (fluorotrichloromethane). Thus, the ODP of CFC-11 is defined to be 1.0. Other CFCs and HCFCs have ODPs that range from 0.01 to 1.0. HFCs have zero ODP because they do not contain chlorine.

As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

The transitional phrase “consisting of” excludes any element, step, or ingredient not specified. If in the claim such would close the claim to the inclusion of materials other than those recited except for impurities ordinarily associated therewith. When the phrase “consists of” appears in a clause of the body of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole.

The transitional phrase “consisting essentially of” is used to define a composition, method or apparatus that includes materials, steps, features, components, or elements, in addition to those literally disclosed provided that these additional included materials, steps, features, components, or elements do materially affect the basic and novel characteristic(s) of the claimed invention. The term ‘consisting essentially of’ occupies a middle ground between “comprising” and ‘consisting of’.

Where applicants have defined an invention or a portion thereof with an open-ended term such as “comprising,” it should be readily understood that (unless otherwise stated) the description should be interpreted to also describe such an invention using the terms “consisting essentially of” or “consisting of.”

Also, use of “a” or “an” are employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the disclosed compositions, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety, unless a particular passage is cited. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

In accordance with the present invention, there is provided a cascade refrigeration system having at least two refrigeration loops for circulating a refrigerant through each loop. Such a cascade system is shown generally at 10 in FIG. 1. The cascade refrigeration system of the present invention has at least two refrigeration loops, including a first, or lower loop 12 as shown in FIG. 1, which is a low temperature loop, and a second, or upper loop 14 as shown in FIG. 1, which is a medium temperature loop 14. Each circulates a refrigerant therethrough.

As shown in FIG. 1, the cascade refrigeration system of the present invention includes a first expansion device 16. The first expansion device has an inlet 16 a and an outlet 16 b. The first expansion device reduces the pressure and temperature of a first refrigerant liquid which circulates through the first or low temperature loop.

The cascade refrigeration system of the present invention also includes an evaporator 18 as shown in FIG. 1. The evaporator has an inlet 18 a and an outlet 18 b. The first refrigerant liquid from the first expansion device enters the evaporator through the evaporator inlet and is evaporated in the evaporator to form a first refrigerant vapor. This produces cooling in the first, or low temperature circuit at a body to be cooled, such as food in a low temperature display case. The first refrigerant vapor then circulates to the outlet of the evaporator.

The cascade refrigeration system of the present invention also includes a first compressor 20. The first compressor has an inlet 20 a and an outlet 20 b. The first refrigerant vapor from the evaporator circulates to the inlet of the first compressor and is compressed, thereby increasing the pressure and the temperature of the first refrigerant vapor. The compressed first refrigerant vapor then circulates to the outlet of the first compressor.

The cascade refrigeration system of the present invention also includes a cascade heat exchanger system 22. The heat exchanger has a first inlet 22 a and a first outlet 22 b. The first refrigerant vapor from the first compressor enters the first inlet of the heat exchanger and is condensed in the heat exchanger to form a first refrigerant liquid, thereby rejecting heat. The first refrigerant liquid then circulates to the first outlet of the heat exchanger. The heat exchanger also includes a second inlet 22 c and a second outlet 22 d. A second refrigerant liquid circulates from the second inlet to the second outlet of the heat exchanger and is evaporated to form a second refrigerant vapor, thereby absorbing the heat rejected by the first refrigerant (as it is condensed). This heat is rejected to ambient. The second refrigerant vapor then circulates to the second outlet of the heat exchanger. Thus, in the embodiment of FIG. 1, the heat rejected by the first refrigerant is directly absorbed by the second refrigerant, and this heat is rejected to ambient.

The cascade refrigeration system of the present invention also includes a second compressor 24 as shown in FIG. 1. The second compressor has an inlet 24 a and an outlet 24 b. The second refrigerant vapor from the cascade heat exchanger is drawn into the compressor through the inlet and is compressed, thereby increasing the pressure and temperature of the second refrigerant vapor. The second refrigerant vapor then circulates to the outlet of the second compressor.

The cascade refrigeration system of the present invention also includes a condenser 26 having an inlet 26 a and an outlet 26 b. The second refrigerant from the second compressor circulates from the inlet and is condensed in the condenser to form a second refrigerant liquid. The second refrigerant liquid exits the condenser through the outlet.

The cascade refrigeration system of the present invention also includes a second expansion device 28 having an inlet 28 a and an outlet 28 b. The second refrigerant liquid passes through the second expansion device, which reduces the pressure and temperature of the second refrigerant liquid exiting the condenser. This liquid may be partially vaporized during this expansion. The reduced pressure and temperature second refrigerant liquid circulates to the second inlet of the cascade heat exchanger system from the expansion device.

It should be noted that various modifications to the embodiment as shown in FIG. 1 may be made without departing from the spirit or scope of the present invention. For instance, it may be possible to include multiple cascade heat exchangers instead of a single cascade heat exchanger and multiple first compressors instead of a single first compressor, as shown in the cascade refrigeration system diagram in the publication titled “Price Chopper Remodel Features Hill Phoenix Next Generation Refrigeration System”, May 5, 2008. In addition, a secondary heat transfer loop, as shown in this diagram, which uses a secondary heat transfer fluids such as glycol, may be used with the system of the present invention to transfer heat from bodies to be cooled (e.g., supermarket food display cases) to either the high or low refrigeration loops or both. In this instance the secondary heat transfer loop is used to transfer heat from a body to be cooled to the refrigeration loop, as opposed to a secondary heat transfer loop which is used to transfer heat between the refrigeration loops, as will be described below with respect to FIG. 3.

In accordance with the present invention, either the first refrigerant or the second refrigerant in the cascade system of the embodiment of FIG. 1 may comprise a fluoroolefin. In particular, at least the second refrigerant, i.e., the refrigerant which circulates through the medium temperature loop, comprises a fluoroolefin. However, it is within the scope of the present invention for the first refrigerant, i.e., the refrigerant in the low temperature loop, to comprise a fluoroolefin. In addition, it is also within the scope of the present invention for both the first and the second refrigerants to comprise a fluoroolefin. Additionally, in some embodiments, the first or the second refrigerant may be any of the fluoroolefins or mixtures of fluoroolefins or mixtures of fluoroolefins with additional refrigerants as described herein.

Such fluoroolefins may be selected from the group consisting of:

-   -   (i) fluoroolefins of the formula E- or Z—R¹CH═CHR², wherein R¹         and R² are, independently, C₁ to C₆ perfluoroalkyl groups;     -   (ii) cyclic fluoroolefins of the formula         cyclo-[CX═CY(CZW)_(n)—], wherein X, Y, Z, and W, independently,         are H or F, and n is an integer from 2 to 5; and     -   (iii) fluoroolefins selected from the group consisting of:         tetrafluoroethylene (CF₂═CF₂); hexafluoropropene         (CF₃CF═CF₂);1,2,3,3,3-pentafluoro-1-propene (CHF═CFCF₃),         1,1,3,3,3-pentafluoro-1-propene (CF₂═CHCF₃),         1,1,2,3,3-pentafluoro-1-propene (CF₂═CFCHF₂),         1,2,3,3-tetrafluoro-1-propene (CHF═CFCHF₂),         2,3,3,3-tetrafluoro-1-propene (CH₂═CFCF₃),         1,3,3,3-tetrafluoro-1-propene (CHF═CHCF₃),         1,1,2,3-tetrafluoro-1-propene (CF₂═CFCH₂F),         1,1,3,3-tetrafluoro-1-propene (CF₂═CHCHF₂),         1,2,3,3-tetrafluoro-1-propene (CHF═CFCHF₂),         3,3,3-trifluoro-1-propene (CH₂═CHCF₃), 2,3,3-trifluoro-1-propene         (CHF₂CF═CH₂); 1,1,2-trifluoro-1-propene (CH₃CF═CF₂);         1,2,3-trifluoro-1-propene (CH₂FCF═CF₂);         1,1,3-trifluoro-1-propene (CH₂FCH═CF₂);         1,3,3-trifluoro-1-propene (CHF₂CH═CHF);         1,1,1,2,3,4,4,4-octafluoro-2-butene (CF₃CF═CFCF₃);         1,1,2,3,3,4,4,4-octafluoro-1-butene (CF₃CF₂CF═CF₂);         1,1,1,2,4,4,4-heptafluoro-2-butene (CF₃CF═CHCF₃);         1,2,3,3,4,4,4-heptafluoro-1-butene (CHF═CFCF₂CF₃);         1,1,1,2,3,4,4-heptafluoro-2-butene (CHF₂CF═CFCF₃);         1,3,3,3-tetrafluoro-2-(trifluoromethyl)-1-propene ((CF₃)₂C═CHF);         1,1,3,3,4,4,4-heptafluoro-1-butene (CF₂═CHCF₂CF₃);         1,1,2,3,4,4,4-heptafluoro-1-butene (CF₂═CFCHFCF₃);         1,1,2,3,3,4,4-heptafluoro-1-butene (CF₂═CFCF₂CHF₂);         2,3,3,4,4,4-hexafluoro-1-butene (CF₃CF₂CF═CH₂);         1,3,3,4,4,4-hexafluoro-1-butene (CHF═CHCF₂CF₃);         1,2,3,4,4,4-hexafluoro-1-butene (CHF═CFCHFCF₃);         1,2,3,3,4,4-hexafluoro-1-butene (CHF═CFCF₂CHF₂);         1,1,2,3,4,4-hexafluoro-2-butene (CHF₂CF═CFCHF₂);         1,1,1,2,3,4-hexafluoro-2-butene (CH₂FCF═CFCF₃);         1,1,1,2,4,4-hexafluoro-2-butene (CHF₂CH═CFCF₃);         1,1,1,3,4,4-hexafluoro-2-butene (CF₃CH═CFCHF₂);         1,1,2,3,3,4-hexafluoro-1-butene (CF₂═CFCF₂CH₂F);         1,1,2,3,4,4-hexafluoro-1-butene (CF₂═CFCHFCHF₂);         3,3,3-trifluoro-2-(trifluoromethyl)-1-propene (CH₂═C(CF₃)₂);         1,1,1,2,4-pentafluoro-2-butene (CH₂FCH═CFCF₃);         1,1,1,3,4-pentafluoro-2-butene (CF₃CH═CFCH₂F);         3,3,4,4,4-pentafluoro-1-butene (CF₃CF₂CH═CH₂);         1,1,1,4,4-pentafluoro-2-butene (CHF₂CH═CHCF₃);         1,1,1,2,3-pentafluoro-2-butene (CH₃CF═CFCF₃);         2,3,3,4,4-pentafluoro-1-butene (CH₂═CFCF₂CHF₂);         1,1,2,4,4-pentafluoro-2-butene (CHF₂CF═CHCHF₂);         1,1,2,3,3-pentafluoro-1-butene (CH₃CF₂CF═CF₂);         1,1,2,3,4-pentafluoro-2-butene (CH₂FCF═CFCHF₂);         1,1,3,3,3-pentafluoro-2-methyl-1-propene (CF₂═C(CF₃)(CH₃));         2-(difluoromethyl)-3,3,3-trifluoro-1-propene (CH₂═C(CHF₂)(CF₃));         2,3,4,4,4-pentafluoro-1-butene (CH₂═CFCHFCF₃);         1,2,4,4,4-pentafluoro-1-butene (CHF═CFCH₂CF₃);         1,3,4,4,4-pentafluoro-1-butene (CHF═CHCHFCF₃);         1,3,3,4,4-pentafluoro-1-butene (CHF═CHCF₂CHF₂);         1,2,3,4,4-pentafluoro-1-butene (CHF═CFCHFCHF₂);         3,3,4,4-tetrafluoro-1-butene (CH₂═CHCF₂CHF₂);         1,1-difluoro-2-(difluoromethyl)-1-propene (CF₂═C(CHF₂)(CH₃));         1,3,3,3-tetrafluoro-2-methyl-1-propene (CHF═C(CF₃)(CH₃));         3,3-difluoro-2-(difluoromethyl)-1-propene (CH₂═C(CHF₂)₂);         1,1,1,2-tetrafluoro-2-butene (CF₃CF═CHCH₃);         1,1,1,3-tetrafluoro-2-butene (CH₃CF═CHCF₃);         1,1,1,2,3,4,4,5,5,5-decafluoro-2-pentene (CF₃CF═CFCF₂CF₃);         1,1,2,3,3,4,4,5,5,5-decafluoro-1-pentene (CF₂═CFCF₂CF₂CF₃);         1,1,1,4,4,4-hexafluoro-2-(trifluoromethyl)-2-butene         ((CF₃)₂C═CHCF₃); 1,1,1,2,4,4,5,5,5-nonafluoro-2-pentene         (CF₃CF═CHCF₂CF₃); 1,1,1,3,4,4,5,5,5-nonafluoro-2-pentene         (CF₃CH═CFCF₂CF₃); 1,2,3,3,4,4,5,5,5-nonafluoro-1-pentene         (CHF═CFCF₂CF₂CF₃); 1,1,3,3,4,4,5,5,5-nonafluoro-1-pentene         (CF₂═CHCF₂CF₂CF₃); 1,1,2,3,3,4,4,5,5-nonafluoro-1-pentene         (CF₂═CFCF₂CF₂CHF₂); 1,1,2,3,4,4,5,5,5-nonafluoro-2-pentene         (CHF₂CF═CFCF₂CF₃); 1,1,1,2,3,4,4,5,5-nonafluoro-2-pentene         (CF₃CF═CFCF₂CHF₂); 1,1,1,2,3,4,5,5,5-nonafluoro-2-pentene         (CF₃CF═CFCHFCF₃);         1,2,3,4,4,4-hexafluoro-3-(trifluoromethyl)-1-butene         (CHF═CFCF(CF₃)₂);         1,1,2,4,4,4-hexafluoro-3-(trifluoromethyl)-1-butene         (CF₂═CFCH(CF₃)₂);         1,1,1,4,4,4-hexafluoro-2-(trifluoromethyl)-2-butene         (CF₃CH═C(CF₃)₂);         1,1,3,4,4,4-hexafluoro-3-(trifluoromethyl)-1-butene         (CF₂═CHCF(CF₃)₂); 2,3,3,4,4,5,5,5-octafluoro-1-pentene         (CH₂═CFCF₂CF₂CF₃); 1,2,3,3,4,4,5,5-octafluoro-1-pentene         (CHF═CFCF₂CF₂CHF₂);         3,3,4,4,4-pentafluoro-2-(trifluoromethyl)-1-butene         (CH₂═C(CF₃)CF₂CF₃);         1,1,4,4,4-pentafluoro-3-(trifluoromethyl)-1-butene         (CF₂═CHCH(CF₃)₂);         1,3,4,4,4-pentafluoro-3-(trifluoromethyl)-1-butene         (CHF═CHCF(CF₃)₂);         1,1,4,4,4-pentafluoro-2-(trifluoromethyl)-1-butene         (CF₂═C(CF₃)CH₂CF₃);         3,4,4,4-tetrafluoro-3-(trifluoromethyl)-1-butene         ((CF₃)₂CFCH═CH₂); 3,3,4,4,5,5,5-heptafluoro-1-pentene         (CF₃CF₂CF₂CH═CH₂); 2,3,3,4,4,5,5-heptafluoro-1-pentene         (CH₂═CFCF₂CF₂CHF₂); 1,1,3,3,5,5,5-heptafluoro-1-butene         (CF₂═CHCF₂CH₂CF₃); 1,1,1,2,4,4,4-heptafluoro-3-methyl-2-butene         (CF₃CF═C(CF₃)(CH₃));         2,4,4,4-tetrafluoro-3-(trifluoromethyl)-1-butene         (CH₂═CFCH(CF₃)₂);         1,4,4,4-tetrafluoro-3-(trifluoromethyl)-1-butene         (CHF═CHCH(CF₃)₂);         1,1,1,4-tetrafluoro-2-(trifluoromethyl)-2-butene         (CH₂FCH═C(CF₃)₂);         1,1,1,3-tetrafluoro-2-(trifluoromethyl)-2-butene         (CH₃CF═C(CF₃)₂); 1,1,1-trifluoro-2-(trifluoromethyl)-2-butene         ((CF₃)₂C═CHCH₃); 3,4,4,5,5,5-hexafluoro-2-pentene         (CF₃CF₂CF═CHCH₃); 1,1,1,4,4,4-hexafluoro-2-methyl-2-butene         (CF₃C(CH₃)═CHCF₃); 3,3,4,5,5,5-hexafluoro-1-pentene         (CH₂═CHCF₂CHFCF₃); 4,4,4-trifluoro-2-(trifluoromethyl)-1-butene         (CH₂═C(CF₃)CH₂CF₃);         1,1,2,3,3,4,4,5,5,6,6,6-dodecafluoro-1-hexene (CF₃(CF₂)₃CF═CF₂);         1,1,1,2,2,3,4,5,5,6,6,6-dodecafluoro-3-hexene         (CF₃CF₂CF═CFCF₂CF₃);         1,1,1,4,4,4-hexafluoro-2,3-bis(trifluoromethyl)-2-butene         ((CF₃)₂C═C(CF₃)₂);         1,1,1,2,3,4,5,5,5-nonafluoro-4-(trifluoromethyl)-2-pentene         ((CF₃)₂CFCF═CFCF₃);         1,1,1,4,4,5,5,5-octafluoro-2-(trifluoromethyl)-2-pentene         ((CF₃)₂C═CHC₂F₅);         1,1,1,3,4,5,5,5-octafluoro-4-(trifluoromethyl)-2-pentene         ((CF₃)₂CFCF═CHCF₃); 3,3,4,4,5,5,6,6,6-nonafluoro-1-hexene         (CF₃CF₂CF₂CF₂CH═CH₂);         4,4,4-trifluoro-3,3-bis(trifluoromethyl)-1-butene         (CH₂═CHC(CF₃)₃);         1,1,1,4,4,4-hexafluoro-3-methyl-2-(trifluoromethyl)-2-butene         ((CF₃)₂C═C(CH₃)(CF₃));         2,3,3,5,5,5-hexafluoro-4-(trifluoromethyl)-1-pentene         (CH₂═CFCF₂CH(CF₃)₂);         1,1,1,2,4,4,5,5,5-nonafluoro-3-methyl-2-pentene         (CF₃CF═C(CH₃)CF₂CF₃);         1,1,1,5,5,5-hexafluoro-4-(trifluoromethyl)-2-pentene         (CF₃CH═CHCH(CF₃)₂); 3,4,4,5,5,6,6,6-octafluoro-2-hexene         (CF₃CF₂CF₂CF═CHCH₃); 3,3,4,4,5,5,6,6-octafluoro1-hexene         (CH₂═CHCF₂CF₂CF₂CHF₂);         1,1,1,4,4-pentafluoro-2-(trifluoromethyl)-2-pentene         ((CF₃)₂C═CHCF₂CH₃);         4,4,5,5,5-pentafluoro-2-(trifluoromethyl)-1-pentene         (CH₂═C(CF₃)CH₂C₂F₅);         3,3,4,4,5,5,5-heptafluoro-2-methyl-1-pentene         (CF₃CF₂CF₂C(CH₃)═CH₂); 4,4,5,5,6,6,6-heptafluoro-2-hexene         (CF₃CF₂CF₂CH═CHCH₃); 4,4,5,5,6,6,6-heptafluoro-1-hexene         (CH₂═CHCH₂CF₂C₂F₅); 1,1,1,2,2,3,4-heptafluoro-3-hexene         (CF₃CF₂CF═CFC₂H₅);         4,5,5,5-tetrafluoro-4-(trifluoromethyl)-1-pentene         (CH₂═CHCH₂CF(CF₃)₂);         1,1,1,2,5,5,5-heptafluoro-4-methyl-2-pentene         (CF₃CF═CHCH(CF₃)(CH₃));         1,1,1,3-tetrafluoro-2-(trifluoromethyl)-2-pentene         ((CF₃)₂C═CFC₂H₅);         1,1,1,2,3,4,4,5,5,6,6,7,7,7-tetradecafluoro-2-heptene         (CF₃CF═CFCF₂CF₂C₂F₅);         1,1,1,2,2,3,4,5,5,6,6,7,7,7-tetradecafluoro-3-heptene         (CF₃CF₂CF═CFCF₂C₂F₅);         1,1,1,3,4,4,5,5,6,6,7,7,7-tridecafluoro-2-heptene         (CF₃CH═CFCF₂CF₂C₂F₅);         1,1,1,2,4,4,5,5,6,6,7,7,7-tridecafluoro-2-heptene         (CF₃CF═CHCF₂CF₂C₂F₅);         1,1,1,2,2,4,5,5,6,6,7,7,7-tridecafluoro-3-heptene         (CF₃CF₂CH═CFCF₂C₂F₅); and         1,1,1,2,2,3,5,5,6,6,7,7,7-tridecafluoro-3-heptene         (CF₃CF₂CF═CHCF₂C₂F₅).

In some embodiments, fluoroolefins are compounds, which comprise carbon atoms, fluorine atoms and optionally hydrogen or chlorine atoms. In one embodiment, the fluoroolefins used in the compositions of the present invention comprise compounds with 2 to 12 carbon atoms. In another embodiment the fluoroolefins comprise compounds with 3 to 10 carbon atoms, and in yet another embodiment the fluoroolefins comprise compounds with 3 to 7 carbon atoms. Representative fluoroolefins include but are not limited to all compounds as listed in Table 1, Table 2, and Table 3.

In one embodiment of the present invention the first refrigerant is selected from fluoroolefins having the formula E- or Z—R¹CH═CHR² (Formula (i)), wherein R¹ and R² are, independently, C₁ to C₆ perfluoroalkyl groups. Examples of R¹ and R² groups include, but are not limited to, CF₃, C₂F₅, CF₂CF₂CF₃, CF(CF₃)₂, CF₂CF₂CF₂CF₃, CF(CF₃)CF₂CF₃, CF₂CF(CF₃)₂, C(CF₃)₃, CF₂CF₂CF₂CF₂CF₃, CF₂CF₂CF(CF₃)₂, C(CF₃)₂C₂F₅, CF₂CF₂CF₂CF₂CF₂CF₃, CF(CF₃)CF₂CF₂C₂F₅, and C(CF₃)₂CF₂C₂F₅. In one embodiment the fluoroolefins of Formula (i) have at least 4 carbon atoms in the molecule. In another embodiment, the first refrigerant is selected from fluoroolefins of Formula (i) having at least 5 carbon atoms in the molecule. In yet another embodiment, the first refrigerant is selected from fluoroolefins of Formula (i) having at least 6 carbon atoms in the molecule. Exemplary, non-limiting Formula (i) compounds are presented in Table 1.

TABLE 1 Code Structure Chemical Name F11E CF₃CH═CHCF₃ 1,1,1,4,4,4-hexafluorobut-2-ene F12E CF₃CH═CHC₂F₅ 1,1,1,4,4,5,5,5-octafluoropent-2-ene F13E CF₃CH═CHCF₂C₂F₅ 1,1,1,4,4,5,5,6,6,6-decafluorohex-2-ene F13iE CF₃CH═CHCF(CF₃)₂ 1,1,1,4,5,5,5-heptafluoro-4-(trifluoromethyl)pent-2-ene F22E C₂F₅CH═CHC₂F₅ 1,1,1,2,2,5,5,6,6,6-decafluorohex-3-ene F14E CF₃CH═CH(CF₂)₃CF₃ 1,1,1,4,4,5,5,6,6,7,7,7-dodecafluorohept-2-ene F14iE CF₃CH═CHCF₂CF—(CF₃)₂ 1,1,1,4,4,5,6,6,6-nonafluoro-5-(trifluoromethyl)hex-2-ene F14sE CF₃CH═CHCF(CF₃)—C₂F₅ 1,1,1,4,5,5,6,6,6-nonfluoro-4-(trifluoromethyl)hex-2-ene F14tE CF₃CH═CHC(CF₃)₃ 1,1,1,5,5,5-hexafluoro-4,4-bis(trifluoromethyl)pent-2-ene F23E C₂F₅CH═CHCF₂C₂F₅ 1,1,1,2,2,5,5,6,6,7,7,7-dodecafluorohept-3-ene F23iE C₂F₅CH═CHCF(CF₃)₂ 1,1,1,2,2,5,6,6,6-nonafluoro-5-(trifluoromethyl)hex-3-ene F15E CF₃CH═CH(CF₂)₄CF₃ 1,1,1,4,4,5,5,6,6,7,7,8,8,8-tetradecafluorooct-2-ene F15iE CF₃CH═CH—CF₂CF₂CF(CF₃)₂ 1,1,1,4,4,5,5,6,7,7,7-undecafluoro-6-(trifluoromethyl)hept- 2-ene F15tE CF₃CH═CH—C(CF₃)₂C₂F₅ 1,1,1,5,5,6,6,6-octafluoro-4,4-bis(trifluoromethyl)hex-2- ene F24E C₂F₅CH═CH(CF₂)₃CF₃ 1,1,1,2,2,5,5,6,6,7,7,8,8,8-tetradecafluorooct-3-ene F24iE C₂F₅CH═CHCF₂CF—(CF₃)₂ 1,1,1,2,2,5,5,6,7,7,7-undecafluoro-6-(trifluoromethyl)hept- 3-ene F24sE C₂F₅CH═CHCF(CF₃)—C₂F₅ 1,1,1,2,2,5,6,6,7,7,7-undecafluoro-5-(trifluoromethyl)hept- 3-ene F24tE C₂F₅CH═CHC(CF₃)₃ 1,1,1,2,2,6,6,6-octafluoro-5,5-bis(trifluoromethyl)hex-3- ene F33E C₂F₅CF₂CH═CH—CF₂C₂F₅ 1,1,1,2,2,3,3,6,6,7,7,8,8,8-tetradecafluorooct-4-ene F3i3iE (CF₃)₂CFCH═CHCF(CF₃)₂ 1,1,1,2,5,6,6,6-octafluoro-2,5-bis(trifluoromethyl)hex-3- ene F33iE C₂F₅CF₂CH═CH—CF(CF₃)₂ 1,1,1,2,5,5,6,6,7,7,7-undecafluoro-2-(trifluoromethyl)hept- 3-ene F16E CF₃CH═CH(CF₂)₅CF₃ 1,1,1,4,4,5,5,6,6,7,7,8,8,9,9,9-hexadecafluoronon-2-ene F16sE CF₃CH═CHCF(CF₃)(CF₂)₂C₂F₅ 1,1,1,4,5,5,6,6,7,7,8,8,8-tridecafluoro-4- (trifluoromethyl)hept-2-ene F16tE CF₃CH═CHC(CF₃)₂CF₂C₂F₅ 1,1,1,6,6,6-octafluoro-4,4-bis(trifluoromethyl)hept-2-ene F25E C₂F₅CH═CH(CF₂)₄CF₃ 1,1,1,2,2,5,5,6,6,7,7,8,8,9,9,9-hexadecafluoronon-3-ene F25iE C₂F₅CH═CH—CF₂CF₂CF(CF₃)₂ 1,1,1,2,2,5,5,6,6,7,8,8,8-tridecafluoro-7- (trifluoromethyl)oct-3-ene F25tE C₂F₅CH═CH—C(CF₃)₂C₂F₅ 1,1,1,2,2,6,6,7,7,7-decafluoro-5,5- bis(trifluoromethyl)hept-3-ene F34E C₂F₅CF₂CH═CH—(CF₂)₃CF₃ 1,1,1,2,2,3,3,6,6,7,7,8,8,9,9,9-hexadecafluoronon-4-ene F34iE C₂F₅CF₂CH═CH—CF₂CF(CF₃)₂ 1,1,1,2,2,3,3,6,6,7,8,8,8-tridecafluoro-7- (trifluoromethyl)oct-4-ene F34sE C₂F₅CF₂CH═CH—CF(CF₃)C₂F₅ 1,1,1,2,2,3,3,6,7,7,8,8,8-tridecafluoro-6- (trifluoromethyl)oct-4-ene F34tE C₂F₅CF₂CH═CH—C(CF₃)₃ 1,1,1,5,5,6,6,7,7,7-decafluoro-2,2- bis(trifluoromethyl)hept-3-ene F3i4E (CF₃)₂CFCH═CH—(CF₂)₃CF₃ 1,1,1,2,5,5,6,6,7,7,8,8,8-tridecafluoro- 2(trifluoromethyl)oct-3-ene F3i4iE (CF₃)₂CFCH═CH—CF₂CF(CF₃)₂ 1,1,1,2,5,5,6,7,7,7-decafluoro-2,6- bis(trifluoromethyl)hept-3-ene F3i4sE (CF₃)₂CFCH═CH—CF(CF₃)C₂F₅ 1,1,1,2,5,6,6,7,7,7-decafluoro-2,5- bis(trifluoromethyl)hept-3-ene F3i4tE (CF₃)₂CFCH═CH—C(CF₃)₃ 1,1,1,2,6,6,6-heptafluoro-2,5,5-tris(trifluoromethyl)hex-3- ene F26E C₂F₅CH═CH(CF₂)₅CF₃ 1,1,1,2,2,5,5,6,6,7,7,8,8,9,9,10,10,10-octadecafluorodec- 3-ene F26sE C₂F₅CH═CHCF(CF₃)(CF₂)₂C₂F₅ 1,1,1,2,2,5,6,6,7,7,8,8,9,9,9-pentadecafluoro-5- (trifluoromethyl)non-3-ene F26tE C₂F₅CH═CHC(CF₃)₂CF₂C₂F₅ 1,1,1,2,2,6,6,7,7,8,8,8-dodecafluoro-5,5- bis(trifluoromethyl)oct-3-ene F35E C₂F₅CF₂CH═CH—(CF₂)₄CF₃ 1,1,1,2,2,3,3,6,6,7,7,8,8,9,9,10,10,10-octadecafluorodec- 4-ene F35iE C₂F₅CF₂CH═CH— 1,1,1,2,2,3,3,6,6,7,7,8,9,9,9-pentadecafluoro-8- CF₂CF₂CF(CF₃)₂ (trifluoromethyl)non-4-ene F35tE C₂F₅CF₂CH═CH—C(CF₃)₂C₂F₅ 1,1,1,2,2,3,3,7,7,8,8,8-dodecafluoro-6,6- bis(trifluoromethyl)oct-4-ene F3i5E (CF₃)₂CFCH═CH—(CF₂)₄CF₃ 1,1,1,2,5,5,6,6,7,7,8,8,9,9,9-pentadecafluoro-2- (trifluoromethyl)non-3-ene F3i5iE (CF₃)₂CFCH═CH— 1,1,1,2,5,5,6,6,7,8,8,8-dodecafluoro-2,7- CF₂CF₂CF(CF₃)₂ bis(trifluoromethyl)oct-3-ene F3i5tE (CF₃)₂CFCH═CH—C(CF₃)₂C₂F₅ 1,1,1,2,6,6,7,7,7-nonafluoro-2,5,5- tris(trifluoromethyl)hept-3-ene F44E CF₃(CF₂)₃CH═CH—(CF₂)₃CF₃ 1,1,1,2,2,3,3,4,4,7,7,8,8,9,9,10,10,10-octadecafluorodec- 5-ene F44iE CF₃(CF₂)₃CH═CH—CF₂CF(CF₃)₂ 1,1,1,2,3,3,6,6,7,7,8,8,9,9,9-pentadecafluoro-2- (trifluoromethyl)non-4-ene F44sE CF₃(CF₂)₃CH═CH—CF(CF₃)C₂F₅ 1,1,1,2,2,3,6,6,7,7,8,8,9,9,9-pentadecafluoro-3- (trifluoromethyl)non-4-ene F44tE CF₃(CF₂)₃CH═CH—C(CF₃)₃ 1,1,1,5,5,6,6,7,7,8,8,8-dodecafluoro-2,2,- bis(trifluoromethyl)oct-3-ene F4i4iE (CF₃)₂CFCF₂CH═CH— 1,1,1,2,3,3,6,6,7,8,8,8-dodecafluoro-2,7- CF₂CF(CF₃)₂ bis(trifluoromethyl)oct-4-ene F4i4sE (CF₃)₂CFCF₂CH═CH— 1,1,1,2,3,3,6,7,7,8,8,8-dodecafluoro-2,6- CF(CF₃)C₂F₅ bis(trifluoromethyl)oct-4-ene F4i4tE (CF₃)₂CFCF₂CH═CH—C(CF₃)₃ 1,1,1,5,5,6,7,7,7-nonafluoro-2,2,6- tris(trifluoromethyl)hept-3-ene F4s4sE C₂F₅CF(CF₃)CH═CH— 1,1,1,2,2,3,6,7,7,8,8,8-dodecafluoro-3,6- CF(CF₃)C₂F₅ bis(trifluoromethyl)oct-4-ene F4s4tE C₂F₅CF(CF₃)CH═CH—C(CF₃)₃ 1,1,1,5,6,6,7,7,7-nonafluoro-2,2,5- tris(trifluoromethyl)hept-3-ene F4t4tE (CF₃)₃CCH═CH—C(CF₃)₃ 1,1,1,6,6,6-hexafluoro-2,2,5,5- tetrakis(trifluoromethyl)hex-3-ene

Compounds of Formula (i) may be prepared by contacting a perfluoroalkyl iodide of the formula R¹I with a perfluoroalkyltrihydroolefin of the formula R²CH═CH₂ to form a trihydroiodoperfluoroalkane of the formula R¹CH₂CHIR². This trihydroiodoperfluoroalkane can then be dehydroiodinated to form R¹CH═CHR². Alternatively, the olefin R¹CH═CHR² may be prepared by dehydroiodination of a trihydroiodoperfluoroalkane of the formula R¹CHICH₂R² formed in turn by reacting a perfluoroalkyl iodide of the formula R²I with a perfluoroalkyltrihydroolefin of the formula R¹CH═CH₂.

The contacting of a perfluoroalkyl iodide with a perfluoroalkyltrihydroolefin may take place in batch mode by combining the reactants in a suitable reaction vessel capable of operating under the autogenous pressure of the reactants and products at reaction temperature. Suitable reaction vessels include fabricated from stainless steels, in particular of the austenitic type, and the well-known high nickel alloys such as Monel® nickel-copper alloys, Hastelloy® nickel based alloys and Inconel® nickel-chromium alloys.

Alternatively, the reaction may be conducted in semi-batch mode in which the perfluoroalkyltrihydroolefin reactant is added to the perfluoroalkyl iodide reactant by means of a suitable addition apparatus such as a pump at the reaction temperature.

The ratio of perfluoroalkyl iodide to perfluoroalkyltrihydroolefin should be between about 1:1 to about 4:1, preferably from about 1.5:1 to 2.5:1. Ratios less than 1.5:1 tend to result in large amounts of the 2:1 adduct as reported by Jeanneaux, et. al. in Journal of Fluorine Chemistry, Vol. 4, pages 261-270 (1974).

Preferred temperatures for contacting of said perfluoroalkyl iodide with said perfluoroalkyltrihydroolefin are preferably within the range of about 150° C. to 300° C., preferably from about 170° C. to about 250° C., and most preferably from about 180° C. to about 230° C.

Suitable contact times for the reaction of the perfluoroalkyl iodide with the perfluoroalkyltrihydroolefin are from about 0.5 hour to 18 hours, preferably from about 4 to about 12 hours.

The trihydroiodoperfluoroalkane prepared by reaction of the perfluoroalkyl iodide with the perfluoroalkyltrihydroolefin may be used directly in the dehydroiodination step or may preferably be recovered and purified by distillation prior to the dehydroiodination step.

The dehydroiodination step is carried out by contacting the trihydroiodoperfluoroalkane with a basic substance. Suitable basic substances include alkali metal hydroxides (e.g., sodium hydroxide or potassium hydroxide), alkali metal oxide (for example, sodium oxide), alkaline earth metal hydroxides (e.g., calcium hydroxide), alkaline earth metal oxides (e.g., calcium oxide), alkali metal alkoxides (e.g., sodium methoxide or sodium ethoxide), aqueous ammonia, sodium amide, or mixtures of basic substances such as soda lime. Preferred basic substances are sodium hydroxide and potassium hydroxide.

Said contacting of the trihydroiodoperfluoroalkane with a basic substance may take place in the liquid phase preferably in the presence of a solvent capable of dissolving at least a portion of both reactants. Solvents suitable for the dehydroiodination step include one or more polar organic solvents such as alcohols (e.g., methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and tertiary butanol), nitriles (e.g., acetonitrile, propionitrile, butyronitrile, benzonitrile, or adiponitrile), dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, or sulfolane. The choice of solvent may depend on the boiling point product and the ease of separation of traces of the solvent from the product during purification. Typically, ethanol or isopropanol are good solvents for the reaction.

Typically, the dehydroiodination reaction may be carried out by addition of one of the reactants (either the basic substance or the trihydroiodoperfluoroalkane) to the other reactant in a suitable reaction vessel. Said reaction may be fabricated from glass, ceramic, or metal and is preferably agitated with an impeller or stirring mechanism.

Temperatures suitable for the dehydroiodination reaction are from about 10° C. to about 100° C., preferably from about 20° C. to about 70° C. The dehydroiodination reaction may be carried out at ambient pressure or at reduced or elevated pressure. Of note are dehydroiodination reactions in which the compound of Formula (i) is distilled out of the reaction vessel as it is formed.

Alternatively, the dehydroiodination reaction may be conducted by contacting an aqueous solution of said basic substance with a solution of the trihydroiodoperfluoroalkane in one or more organic solvents of lower polarity such as an alkane (e.g., hexane, heptane, or octane), aromatic hydrocarbon (e.g., toluene), halogenated hydrocarbon (e.g., methylene chloride, chloroform, carbon tetrachloride, or perchloroethylene), or ether (e.g., diethyl ether, methyl tert-butyl ether, tetrahydrofuran, 2-methyl tetrahydrofuran, dioxane, dimethoxyethane, diglyme, or tetraglyme) in the presence of a phase transfer catalyst. Suitable phase transfer catalysts include quaternary ammonium halides (e.g., tetrabutylammonium bromide, tetrabutylammonium hydrosulfate, triethylbenzylammonium chloride, dodecyltrimethylammonium chloride, and tricaprylylmethylammonium chloride), quaternary phosphonium halides (e.g., triphenylmethylphosphonium bromide and tetraphenylphosphonium chloride), or cyclic polyether compounds known in the art as crown ethers (e.g., 18-crown-6 and 15-crown-5).

Alternatively, the dehydroiodination reaction may be conducted in the absence of solvent by adding the trihydroiodoperfluoroalkane to a solid or liquid basic substance.

Suitable reaction times for the dehydroiodination reactions are from about 15 minutes to about six hours or more depending on the solubility of the reactants. Typically the dehydroiodination reaction is rapid and requires about 30 minutes to about three hours for completion. The compound of Formula (i) may be recovered from the dehydroiodination reaction mixture by phase separation after addition of water, by distillation, or by a combination thereof.

In another embodiment of the present invention, the first refrigerant is selected from fluoroolefins comprising cyclic fluoroolefins (cyclo-[CX═CY(CZW)_(n)—] (Formula (ii)), wherein X, Y, Z, and W are independently selected from H and F, and n is an integer from 2 to 5). In one embodiment the fluoroolefins of Formula (ii), have at least about 3 carbon atoms in the molecule. In another embodiment, the fluoroolefins of Formula (ii) have at least about 4 carbon atoms in the molecule. In another embodiment, the fluoroolefins of Formula (ii) have at least about 5 carbon atoms in the molecule. In yet another embodiment, the fluoroolefins of Formula (ii) have at least about 6 carbon atoms in the molecule. Representative cyclic fluoroolefins of Formula (ii) are listed in Table 2.

TABLE 2 Cyclic fluoroolefins Structure Chemical name HFO-C1316CC cyclo-CF₂CF₂CF═CF— 1,2,3,3,4,4- hexafluorocyclobutene HFO-C1334CC cyclo-CF₂CF₂CH═CH— 3,3,4,4- tetrafluorocyclobutene HFO-C1436 Cyclo-CF₂CF₂CF₂CH═CH— 3,3,4,4,5,5,- hexafluorocyclopentene HFO-C1418y Cyclo-CF₂CF═CFCF₂CF₂— 1,2,3,3,4,4,5,5- octafluorocyclopentene HFO-C151-10y Cyclo- 1,2,3,3,4,4,5,5,6,6- CF₂CF═CFCF₂CF₂CF₂— decafluorocyclohexene

The first refrigerant of the present invention may comprise a single compound of Formula (i) or Formula (ii), for example, one of the compounds in Table 1 or Table 2, or may comprise a combination of compounds of Formula (i) or Formula (ii).

In another embodiment, the first refrigerant is selected from fluoroolefins comprising those compounds listed in Table 3.

TABLE 3 Name Structure Chemical name HFO-1225ye CF₃CF═CHF 1,2,3,3,3-pentafluoro-1-propene HFO-1225zc CF₃CH═CF₂ 1,1,3,3,3-pentafluoro-1-propene HFO-1225yc CHF₂CF═CF₂ 1,1,2,3,3-pentafluoro-1-propene HFO-1234ye CHF₂CF═CHF 1,2,3,3-tetrafluoro-1-propene HFO-1234yf CF₃CF═CH₂ 2,3,3,3-tetrafluoro-1-propene HFO-1234ze CF₃CH═CHF 1,3,3,3-tetrafluoro-1-propene HFO-1234yc CH₂FCF═CF₂ 1,1,2,3-tetrafluoro-1-propene HFO-1234zc CHF₂CH═CF₂ 1,1,3,3-tetrafluoro-1-propene HFO-1243yf CHF₂CF═CH₂ 2,3,3-trifluoro-1-propene HFO-1243zf CF₃CH═CH₂ 3,3,3-trifluoro-1-propene HFO-1243yc CH₃CF═CF₂ 1,1,2-trifluoro-1-propene HFO-1243zc CH₂FCH═CF₂ 1,1,3-trifluoro-1-propene HFO-1243ye CH₂FCF═CHF 1,2,3-trifluoro-1-propene HFO-1243ze CHF₂CH═CHF 1,3,3-trifluoro-1-propene HCFO-1233xf CF₃CCl═CH₂ 2-chloro-3,3,3-trifluoro-1-propene HCFO-1233zd CF₃CH═CHCl 1-chloro-3,3,3-trifluoro-1-propene HFO-1318my CF₃CF═CFCF₃ 1,1,1,2,3,4,4,4-octafluoro-2-butene HFO-1318cy CF₃CF₂CF═CF₂ 1,1,2,3,3,4,4,4-octafluoro-1-butene HFO-1327my CF₃CF═CHCF₃ 1,1,1,2,4,4,4-heptafluoro-2-butene HFO-1327ye CHF═CFCF₂CF₃ 1,2,3,3,4,4,4-heptafluoro-1-butene HFO-1327py CHF₂CF═CFCF₃ 1,1,1,2,3,4,4-heptafluoro-2-butene HFO-1327et (CF₃)₂C═CHF 1,3,3,3-tetrafluoro-2- (trifluoromethyl)-1-propene HFO-1327cz CF₂═CHCF₂CF₃ 1,1,3,3,4,4,4-heptafluoro-1-butene HFO-1327cye CF₂═CFCHFCF₃ 1,1,2,3,4,4,4-heptafluoro-1-butene HFO-1327cyc CF₂═CFCF₂CHF₂ 1,1,2,3,3,4,4-heptafluoro-1-butene HFO-1336yf CF₃CF₂CF═CH₂ 2,3,3,4,4,4-hexafluoro-1-butene HFO-1336ze CHF═CHCF₂CF₃ 1,3,3,4,4,4-hexafluoro-1-butene HFO-1336eye CHF═CFCHFCF₃ 1,2,3,4,4,4-hexafluoro-1-butene HFO-1336eyc CHF═CFCF₂CHF₂ 1,2,3,3,4,4-hexafluoro-1-butene HFO-1336pyy CHF₂CF═CFCHF₂ 1,1,2,3,4,4-hexafluoro-2-butene HFO-1336qy CH₂FCF═CFCF₃ 1,1,1,2,3,4-hexafluoro-2-butene HFO-1336pz CHF₂CH═CFCF₃ 1,1,1,2,4,4-hexafluoro-2-butene HFO-1336mzy CF₃CH═CFCHF₂ 1,1,1,3,4,4-hexafluoro-2-butene HFO-1336qc CF₂═CFCF₂CH₂F 1,1,2,3,3,4-hexafluoro-1-butene HFO-1336pe CF₂═CFCHFCHF₂ 1,1,2,3,4,4-hexafluoro-1-butene HFO-1336ft CH₂═C(CF₃)₂ 3,3,3-trifluoro-2-(trifluoromethyl)-1- propene HFO-1345qz CH₂FCH═CFCF₃ 1,1,1,2,4-pentafluoro-2-butene HFO-1345mzy CF₃CH═CFCH₂F 1,1,1,3,4-pentafluoro-2-butene HFO-1345fz CF₃CF₂CH═CH₂ 3,3,4,4,4-pentafluoro-1-butene HFO-1345mzz CHF₂CH═CHCF₃ 1,1,1,4,4-pentafluoro-2-butene HFO-1345sy CH₃CF═CFCF₃ 1,1,1,2,3-pentafluoro-2-butene HFO-1345fyc CH₂═CFCF₂CHF₂ 2,3,3,4,4-pentafluoro-1-butene HFO-1345pyz CHF₂CF═CHCHF₂ 1,1,2,4,4-pentafluoro-2-butene HFO-1345cyc CH₃CF₂CF═CF₂ 1,1,2,3,3-pentafluoro-1-butene HFO-1345pyy CH₂FCF═CFCHF₂ 1,1,2,3,4-pentafluoro-2-butene HFO-1345eyc CH₂FCF₂CF═CHF 1,2,3,3,4-pentafluoro-1-butene HFO-1345ctm CF₂═C(CF₃)(CH₃) 1,1,3,3,3-pentafluoro-2-methyl-1- propene HFO-1345ftp CH₂═C(CHF₂)(CF₃) 2-(difluoromethyl)-3,3,3-trifluoro-1- propene HFO-1345fye CH₂═CFCHFCF₃ 2,3,4,4,4-pentafluoro-1-butene HFO-1345eyf CHF═CFCH₂CF₃ 1,2,4,4,4-pentafluoro-1-butene HFO-1345eze CHF═CHCHFCF₃ 1,3,4,4,4-pentafluoro-1-butene HFO-1345ezc CHF═CHCF₂CHF₂ 1,3,3,4,4-pentafluoro-1-butene HFO-1345eye CHF═CFCHFCHF₂ 1,2,3,4,4-pentafluoro-1-butene HFO-1354fzc CH₂═CHCF₂CHF₂ 3,3,4,4-tetrafluoro-1-butene HFO-1354ctp CF₂═C(CHF₂)(CH₃) 1,1,3,3-tetrafluoro-2-methyl-1- propene HFO-1354etm CHF═C(CF₃)(CH₃) 1,3,3,3-tetrafluoro-2-methyl-1- propene HFO-1354tfp CH₂═C(CHF₂)₂ 2-(difluoromethyl)-3,3-difluoro-1- propene HFO-1354my CF₃CF═CHCH₃ 1,1,1,2-tetrafluoro-2-butene HFO-1354mzy CH₃CF═CHCF₃ 1,1,1,3-tetrafluoro-2-butene HFO-141-10myy CF₃CF═CFCF₂CF₃ 1,1,1,2,3,4,4,5,5,5-decafluoro-2- pentene HFO-141-10cy CF₂═CFCF₂CF₂CF₃ 1,1,2,3,3,4,4,5,5,5-decafluoro-1- pentene HFO-1429mzt (CF₃)₂C═CHCF₃ 1,1,1,4,4,4-hexafluoro-2- (trifluoromethyl)-2-butene HFO-1429myz CF₃CF═CHCF₂CF₃ 1,1,1,2,4,4,5,5,5-nonafluoro-2- pentene HFO-1429mzy CF₃CH═CFCF₂CF₃ 1,1,1,3,4,4,5,5,5-nonafluoro-2- pentene HFO-1429eyc CHF═CFCF₂CF₂CF₃ 1,2,3,3,4,4,5,5,5-nonafluoro-1- pentene HFO-1429czc CF₂═CHCF₂CF₂CF₃ 1,1,3,3,4,4,5,5,5-nonafluoro-1- pentene HFO-1429cycc CF₂═CFCF₂CF₂CHF₂ 1,1,2,3,3,4,4,5,5-nonafluoro-1- pentene HFO-1429pyy CHF₂CF═CFCF₂CF₃ 1,1,2,3,4,4,5,5,5-nonafluoro-2- pentene HFO-1429myyc CF₃CF═CFCF₂CHF₂ 1,1,1,2,3,4,4,5,5-nonafluoro-2- pentene HFO-1429myye CF₃CF═CFCHFCF₃ 1,1,1,2,3,4,5,5,5-nonafluoro-2- pentene HFO-1429eyym CHF═CFCF(CF₃)₂ 1,2,3,4,4,4-hexafluoro-3- (trifluoromethyl)-1-butene HFO-1429cyzm CF₂═CFCH(CF₃)₂ 1,1,2,4,4,4-hexafluoro-3- (trifluoromethyl)-1-butene HFO-1429mzt CF₃CH═C(CF₃)₂ 1,1,1,4,4,4-hexafluoro-2- (trifluoromethyl)-2-butene HFO-1429czym CF₂═CHCF(CF₃)₂ 1,1,3,4,4,4-hexafluoro-3- (trifluoromethyl)-1-butene HFO-1438fy CH₂═CFCF₂CF₂CF₃ 2,3,3,4,4,5,5,5-octafluoro-1- pentene HFO-1438eycc CHF═CFCF₂CF₂CHF₂ 1,2,3,3,4,4,5,5-octafluoro-1- pentene HFO-1438ftmc CH₂═C(CF₃)CF₂CF₃ 3,3,4,4,4-pentafluoro-2- (trifluoromethyl)-1-butene HFO-1438czzm CF₂═CHCH(CF₃)₂ 1,1,4,4,4-pentafluoro-3- (trifluoromethyl)-1-butene HFO-1438ezym CHF═CHCF(CF₃)₂ 1,3,4,4,4-pentafluoro-3- (trifluoromethyl)-1-butene HFO-1438ctmf CF₂═C(CF₃)CH₂CF₃ 1,1,4,4,4-pentafluoro-2- (trifluoromethyl)-1-butene HFO-1447fzy (CF₃)₂CFCH═CH₂ 3,4,4,4-tetrafluoro-3- (trifluoromethyl)-1-butene HFO-1447fz CF₃CF₂CF₂CH═CH₂ 3,3,4,4,5,5,5-heptafluoro-1-pentene HFO-1447fycc CH₂═CFCF₂CF₂CHF₂ 2,3,3,4,4,5,5-heptafluoro-1-pentene HFO-1447czcf CF₂═CHCF₂CH₂CF₃ 1,1,3,3,5,5,5-heptafluoro-1-pentene HFO-1447mytm CF₃CF═C(CF₃)(CH₃) 1,1,1,2,4,4,4-heptafluoro-3-methyl- 2-butene HFO-1447fyz CH₂═CFCH(CF₃)₂ 2,4,4,4-tetrafluoro-3- (trifluoromethyl)-1-butene HFO-1447ezz CHF═CHCH(CF₃)₂ 1,4,4,4-tetrafluoro-3- (trifluoromethyl)-1-butene HFO-1447qzt CH₂FCH═C(CF₃)₂ 1,4,4,4-tetrafluoro-2- (trifluoromethyl)-2-butene HFO-1447syt CH₃CF═C(CF₃)₂ 2,4,4,4-tetrafluoro-2- (trifluoromethyl)-2-butene HFO-1456szt (CF₃)₂C═CHCH₃ 3-(trifluoromethyl)-4,4,4-trifluoro-2- butene HFO-1456szy CF₃CF₂CF═CHCH₃ 3,4,4,5,5,5-hexafluoro-2-pentene HFO-1456mstz CF₃C(CH₃)═CHCF₃ 1,1,1,4,4,4-hexafluoro-2-methyl-2- butene HFO-1456fzce CH₂═CHCF₂CHFCF₃ 3,3,4,5,5,5-hexafluoro-1-pentene HFO-1456ftmf CH₂═C(CF₃)CH₂CF₃ 4,4,4-trifluoro-2-(trifluoromethyl)-1- butene HFO-151-12C CF₃(CF₂)₃CF═CF₂ 1,1,2,3,3,4,4,5,5,6,6,6- dodecafluoro-1-hexene (or perfluoro-1-hexene) HFO-151-12mcy CF₃CF₂CF═CFCF₂CF₃ 1,1,1,2,2,3,4,5,5,6,6,6- dodecafluoro-3-hexene (or perfluoro-3-hexene) HFO-151-12mmtt (CF₃)₂C═C(CF₃)₂ 1,1,1,4,4,4-hexafluoro-2,3- bis(trifluoromethyl)-2-butene HFO-151-12mmzz (CF₃)₂CFCF═CFCF₃ 1,1,1,2,3,4,5,5,5-nonafluoro-4- (trifluoromethyl)-2-pentene HFO-152-11mmtz (CF₃)₂C═CHC₂F₅ 1,1,1,4,4,5,5,5-octafluoro-2- (trifluoromethyl)-2-pentene HFO-152-11mmyyz (CF₃)₂CFCF═CHCF₃ 1,1,1,3,4,5,5,5-octafluoro-4- (trifluoromethyl)-2-pentene PFBE (or HFO- CF₃CF₂CF₂CF₂CH═CH₂ 3,3,4,4,5,5,6,6,6-nonafluoro-1- 1549fz) hexene (or perfluorobutylethylene) HFO-1549fztmm CH₂═CHC(CF₃)₃ 4,4,4-trifluoro-3,3- bis(trifluoromethyl)-1-butene HFO-1549mmtts (CF₃)₂C═C(CH₃)(CF₃) 1,1,1,4,4,4-hexafluoro-3-methyl-2- (trifluoromethyl)-2-butene HFO-1549fycz CH₂═CFCF₂CH(CF₃)₂ 2,3,3,5,5,5-hexafluoro-4- (trifluoromethyl)-1-pentene HFO-1549myts CF₃CF═C(CH₃)CF₂CF₃ 1,1,1,2,4,4,5,5,5-nonafluoro-3- methyl-2-pentene HFO-1549mzzz CF₃CH═CHCH(CF₃)₂ 1,1,1,5,5,5-hexafluoro-4- (trifluoromethyl)-2-pentene HFO-1558szy CF₃CF₂CF₂CF═CHCH₃ 3,4,4,5,5,6,6,6-octafluoro-2-hexene HFO-1558fzccc CH₂═CHCF₂CF₂CF₂CHF₂ 3,3,4,4,5,5,6,6-octafluoro-2-hexene HFO-1558mmtzc (CF₃)₂C═CHCF₂CH₃ 1,1,1,4,4-pentafluoro-2- (trifluoromethyl)-2-pentene HFO-1558ftmf CH₂═C(CF₃)CH₂C₂F₅ 4,4,5,5,5-pentafluoro-2- (trifluoromethyl)-1-pentene HFO-1567fts CF₃CF₂CF₂C(CH₃)═CH₂ 3,3,4,4,5,5,5-heptafluoro-2-methyl- 1-pentene HFO-1567szz CF₃CF₂CF₂CH═CHCH₃ 4,4,5,5,6,6,6-heptafluoro-2-hexene HFO-1567fzfc CH₂═CHCH₂CF₂C₂F₅ 4,4,5,5,6,6,6-heptafluoro-1-hexene HFO-1567sfyy CF₃CF₂CF═CFC₂H₅ 1,1,1,2,2,3,4-heptafluoro-3-hexene HFO-1567fzfy CH₂═CHCH₂CF(CF₃)₂ 4,5,5,5-tetrafluoro-4- (trifluoromethyl)-1-pentene HFO-1567myzzm CF₃CF═CHCH(CF₃)(CH₃) 1,1,1,2,5,5,5-heptafluoro-4-methyl- 2-pentene HFO-1567mmtyf (CF₃)₂C═CFC₂H₅ 1,1,1,3-tetrafluoro-2- (trifluoromethyl)-2-pentene HFO-161-14myy CF₃CF═CFCF₂CF₂C₂F₅ 1,1,1,2,3,4,4,5,5,6,6,7,7,7- tetradecafluoro-2-heptene HFO-161-14mcyy CF₃CF₂CF═CFCF₂C₂F₅ 1,1,1,2,2,3,4,5,5,6,6,7,7,7- tetradecafluoro-2-heptene HFO-162-13mzy CF₃CH═CFCF₂CF₂C₂F₅ 1,1,1,3,4,4,5,5,6,6,7,7,7- tridecafluoro-2-heptene HFC162-13myz CF₃CF═CHCF₂CF₂C₂F₅ 1,1,1,2,4,4,5,5,6,6,7,7,7- tridecafluoro-2-heptene HFO-162-13mczy CF₃CF₂CH═CFCF₂C₂F₅ 1,1,1,2,2,4,5,5,6,6,7,7,7- tridecafluoro-3-heptene HFO-162-13mcyz CF₃CF₂CF═CHCF₂C₂F₅ 1,1,1,2,2,3,5,5,6,6,7,7,7- tridecafluoro-3-heptene PEVE CF₂═CFOCF₂CF₃ pentafluoroethyl trifluorovinyl ether PMVE CF₂═CFOCF₃ trifluoromethyl trifluorovinyl ether

The compounds listed in Table 2 and Table 3 are available commercially or may be prepared by processes known in the art or as described herein.

1,1,1,4,4-pentafluoro-2-butene may be prepared from 1,1,1,2,4,4-hexafluorobutane (CHF₂CH₂CHFCF₃) by dehydrofluorination over solid KOH in the vapor phase at room temperature. The synthesis of 1,1,1,2,4,4-hexafluorobutane is described in U.S. Pat. No. 6,066,768. 1,1,1,4,4,4-hexafluoro-2-butene may be prepared from 1,1,1,4,4,4-hexafluoro-2-iodobutane (CF₃CHICH₂CF₃) by reaction with KOH using a phase transfer catalyst at about 60° C. The synthesis of 1,1,1,4,4,4-hexafluoro-2-iodobutane may be carried out by reaction of perfluoromethyl iodide (CF₃I) and 3,3,3-trifluoropropene (CF₃CH═CH₂) at about 200° C. under autogenous pressure for about 8 hours.

3,4,4,5,5,5-hexafluoro-2-pentene may be prepared by dehydrofluorination of 1,1,1,2,2,3,3-heptafluoropentane (CF₃CF₂CF₂CH₂CH₃) using solid KOH or over a carbon catalyst at 200-300° C. 1,1,1,2,2,3,3-heptafluoropentane may be prepared by hydrogenation of 3,3,4,4,5,5,5-heptafluoro-1-pentene (CF₃CF₂CF₂CH═CH₂).

1,1,1,2,3,4-hexafluoro-2-butene may be prepared by dehydrofluorination of 1,1,1,2,3,3,4-heptafluorobutane (CH₂FCF₂CHFCF₃) using solid KOH.

1,1,1,2,4,4-hexafluoro-2-butene may be prepared by dehydrofluorination of 1,1,1,2,2,4,4-heptafluorobutane (CHF₂CH₂CF₂CF₃) using solid KOH.

1,1,1,3,4,4-hexafluoro2-butene may be prepared by dehydrofluorination of 1,1,1,3,3,4,4-heptafluorobutane (CF₃CH₂CF₂CHF₂) using solid KOH. 1,1,1,2,4-pentafluoro-2-butene may be prepared by dehydrofluorination of 1,1,1,2,2,3-hexafluorobutane (CH₂FCH₂CF₂CF₃) using solid KOH.

1,1,1,3,4-pentafluoro-2-butene may be prepared by dehydrofluorination of 1,1,1,3,3,4-hexafluorobutane (CF₃CH₂CF₂CH₂F) using solid KOH.

1,1,1,3-tetrafluoro-2-butene may be prepared by reacting 1,1,1,3,3-pentafluorobutane (CF₃CH₂CF₂CH₃) with aqueous KOH at 120° C.

1,1,1,4,4,5,5,5-octafluoro-2-pentene may be prepared from (CF₃CHICH₂CF₂CF₃) by reaction with KOH using a phase transfer catalyst at about 60° C. The synthesis of 4-iodo-1,1,1,2,2,5,5,5-octafluoropentane may be carried out by reaction of perfluoroethyliodide (CF₃CF₂I) and 3,3,3-trifluoropropene at about 200° C. under autogenous pressure for about 8 hours.

1,1,1,2,2,5,5,6,6,6-decafluoro-3-hexene may be prepared from 1,1,1,2,2,5,5,6,6,6-decafluoro-3-iodohexane (CF₃CF₂CHICH₂CF₂CF₃) by reaction with KOH using a phase transfer catalyst at about 60° C. The synthesis of 1,1,1,2,2,5,5,6,6,6-decafluoro-3-iodohexane may be carried out by reaction of perfluoroethyliodide (CF₃CF₂I) and 3,3,4,4,4-pentafluoro-1-butene (CF₃CF₂CH═CH₂) at about 200° C. under autogenous pressure for about 8 hours.

1,1,1,4,5,5,5-heptafluoro-4-(trifluoromethyl)-2-pentene may be prepared by the dehydrofluorination of 1,1,1,2,5,5,5-heptafluoro-4-iodo-2-(trifluoromethyl)-pentane (CF₃CHICH₂CF(CF₃)₂) with KOH in isopropanol. CF₃CHICH₂CF(CF₃)₂ is made from reaction of (CF₃)₂CFI with CF₃CH═CH₂ at high temperature, such as about 200° C.

1,1,1,4,4,5,5,6,6,6-decafluoro-2-hexene may be prepared by the reaction of 1,1,1,4,4,4-hexafluoro-2-butene (CF₃CH═CHCF₃) with tetrafluoroethylene (CF₂═CF₂) and antimony pentafluoride (SbF₅).

2,3,3,4,4-pentafluoro-1-butene may be prepared by dehydrofluorination of 1,1,2,2,3,3-hexafluorobutane over fluorided alumina at elevated temperature.

2,3,3,4,4,5,5,5-ocatafluoro-1-pentene may be prepared by dehydrofluorination of 2,2,3,3,4,4,5,5,5-nonafluoropentane over solid KOH.

1,2,3,3,4,4,5,5-octafluoro-1-pentene may be prepared by dehydrofluorination of 2,2,3,3,4,4,5,5,5-nonafluoropentane over fluorided alumina at elevated temperature.

Many of the compounds of Formula 1, Formula 2, Table 1, Table 2 and Table 3 exist as different configurational isomers or stereoisomers. When the specific isomer is not designated, the present invention is intended to include all single configurational isomers, single stereoisomers, or any combination thereof. For instance, F11E is meant to represent the E-isomer, Z-isomer, or any combination or mixture of both isomers in any ratio. As another example, HFO-1225ye is meant to represent the E-isomer, Z-isomer, or any combination or mixture of both isomers in any ratio.

Additionally, the first refrigerant may be any of the single fluoroolefins of Formula (i), Formula (ii), Table 1, Table 2 and Table 3, or may be any combination of the different fluoroolefins from Formula (i), Formula (ii), Table 1, Table 2 and Table 3.

In some embodiments, the first refrigerant may be any combination of a single fluoroolefin or multiple fluoroolefins selected from Formula (i), Formula (ii), Table 1, Table 2 and Table 3 with at least one additional refrigerant selected from hydrofluorocarbons, fluoroethers, hydrocarbons, CF₃I, ammonia (NH₃), carbon dioxide (CO₂), nitrous oxide (N₂O), and mixtures thereof, meaning mixtures of any of the foregoing compounds.

In some embodiments, the first refrigerant may contain hydrofluorocarbons comprising at least one saturated compound containing carbon, hydrogen, and fluorine. Of particular utility are hydrofluorocarbons having 1-7 carbon atoms and having a normal boiling point of from about −90° C. to about 80° C. Hydrofluorocarbons are commercial products available from a number of sources or may be prepared by methods known in the art. Representative hydrofluorocarbon compounds include but are not limited to fluoromethane (CH₃F, HFC-41), difluoromethane (CH₂F₂, HFC-32), trifluoromethane (CHF₃, HFC-23), pentafluoroethane (CF₃CHF₂, HFC-125), 1,1,2,2-tetrafluoroethane (CHF₂CHF₂, HFC-134), 1,1,1,2-tetrafluoroethane (CF₃CH₂F, HFC-134a), 1,1,1-trifluoroethane (CF₃CH₃, HFC-143a), 1,1-difluoroethane (CHF₂CH₃, HFC-152a), fluoroethane (CH₃CH₂F, HFC-161), 1,1,1,2,2,3,3-heptafluoropropane (CF₃CF₂CHF₂, HFC-227ca), 1,1,1,2,3,3,3-heptafluoropropane (CF₃CHFCF₃, HFC-227ea), 1,1,2,2,3,3,-hexafluoropropane (CHF₂CF₂CH F₂, HFC-236ca), 1,1,1,2,2,3-hexafluoropropane (CF₃CF₃CH₂F, HFC-236cb), 1,1,1,2,3,3-hexafluoropropane (CF₃CHFCHF₂, HFC-236ea), 1,1,1,3,3,3-hexafluoropropane (CF₃CH₂CF₃, HFC-236fa), 1,1,2,2,3-pentafluoropropane (CHF₂CF₂CH₂F, HFC-245ca), 1,1,1,2,2-pentafluoropropane (CF₃CF₂CH₃, HFC-245cb), 1,1,2,3,3-pentafluoropropane (CHF₂CHFCHF₂, HFC-245ea), 1,1,1,2,3-pentafluoropropane (CF₃CHFCH₂F, HFC-245eb), 1,1,1,3,3-pentafluoropropane (CF₃CH₂CHF₂, HFC-245fa), 1,2,2,3-tetrafluoropropane (CH₂FCF₂CH₂F, HFC-254ca), 1,1,2,2-tetrafluoropropane (CHF₂CF₂CH₃, HFC-254cb), 1,1,2,3-tetrafluoropropane (CHF₂CHFCH₂F, HFC-254ea), 1,1,1,2-tetrafluoropropane (CF₃CHFCH₃, HFC-254eb), 1,1,3,3-tetrafluoropropane (CHF₂CH₂CHF₂, HFC-254fa), 1,1,1,3-tetrafluoropropane (CF₃CH₂CH₂F, HFC-254fb), 1,1,1-trifluoropropane (CF₃CH₂CH₃, HFC-263fb), 2,2-difluoropropane (CH₃CF₂CH₃, HFC-272ca), 1,2-difluoropropane (CH₂FCHFCH₃, HFC-272ea), 1,3-difluoropropane (CH₂FCH₂CH₂F, HFC-272fa), 1,1-difluoropropane (CHF₂CH₂CH₃, HFC-272fb), 2-fluoropropane (CH₃CHFCH₃, HFC-281ea), 1-fluoropropane (CH₂FCH₂CH₃, HFC-281fa), 1,1,2,2,3,3,4,4-octafluorobutane (CHF₂CF₂CF₂CHF₂, HFC-338pcc), 1,1,1,2,2,4,4,4-octafluorobutane (CF₃CH₂CF₂CF₃, HFC-338mf), 1,1,1,3,3-pentafluorobutane (CF₃CH₂CHF₂, HFC-365mfc), 1,1,1,2,3,4,4,5,5,5-decafluoropentane (CF₃CHFCHFCF₂CF₃, HFC-43-10mee), and 1,1,1,2,2,3,4,5,5,6,6,7,7,7-tetradecafluoroheptane (CF₃CF₂CHFCHFCF₂CF₂CF₃, HFC-63-14mee).

In some embodiments, the first refrigerant may further comprise fluoroethers. Fluoroethers comprise at least one compound having carbon, fluorine, oxygen and optionally hydrogen, chlorine, bromine or iodine. Fluoroethers are commercially available or may be produced by methods known in the art. Representative fluoroethers include but are not limited to nonafluoromethoxybutane (C₄F₉OCH₃, any or all possible isomers or mixtures thereof); nonafluoroethoxybutane (C₄F₉OC₂H₅, any or all possible isomers or mixtures thereof); 2-difluoromethoxy-1,1,1,2-tetrafluoroethane (HFOC-236eaβγ, or CHF₂OCHFCF₃); 1,1-difluoro-2-methoxyethane (HFOC-272fbEβγ,CH₃OCH₂CHF₂); 1,1,1,3,3,3-hexafluoro-2-(fluoromethoxy)propane (HFOC-347mmzEβγ, or CH₂FOCH(CF₃)₂); 1,1,1,3,3,3-hexafluoro-2-methoxypropane (HFOC-356mmzEβγ, or CH₃OCH(CH₃)₂); 1,1,1,2,2-pentafluoro-3-methoxypropane (HFOC-365mcEγδ, or CF₃CF₂CH₂OCH₃); 2-ethoxy-1,1,1,2,3,3,3-heptafluoropropane (HFOC-467mmyEβγ, or CH₃CH₂OCF(CF₃)₂; and mixtures thereof.

In some embodiments, the first refrigerant may further comprise at least one hydrocarbon. Hydrocarbons are compounds having only carbon and hydrogen. Of particular utility are compounds having 3-7 carbon atoms. Hydrocarbons are commercially available through numerous chemical suppliers. Representative hydrocarbons include but are not-limited to propane, n-butane, isobutane, cyclobutane, n-pentane, 2-methylbutane, 2,2-dimethylpropane, cyclopentane, n-hexane, 2-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 3-methylpentane, cyclohexane, n-heptane, cycloheptane, and mixtures thereof. In some embodiments, the disclosed compositions may comprise hydrocarbons containing heteroatoms, such as dimethylether (DME, CH₃OCH₃). DME is commercially available.

In some embodiments, the first refrigerant may further comprise carbon dioxide (CO₂), which is commercially available from various sources or may be prepared by methods known in the art.

In some embodiments, the first refrigerant may further comprise ammonia (NH₃), which is commercially available from various sources or may be prepared by methods known in the art.

In some embodiments, the first refrigerant may further comprise iodotrifluoromethane (CF₃I), which is commercially available from various sources or may be prepared by methods known in the art.

In particular embodiments, the first and the second refrigerants may be as shown in the Table 4 below.

TABLE 4 First Refrigerant for Second Refrigerant for Low Temp Circuit Medium Temp Circuit 1 CO₂ or N₂O HFO-1234yf 2 HFO-1234yf/HFC-32 HFO-1234yf 3 trans HFO-1234ze/HFC-32 HFO-1234yf 4 CO₂ or N₂O HFO-1234yf/HFC-134a 5 HFO-1234yf/HFC-32 HFO-1234yf/HFC-134a 6 trans HFO-1234ze/HFC-32 HFO-1234yf/HFC-134a 7 CO₂ or N₂O HFO-1234yf/HFC-32 8 HFO-1234yf/HFC-32 HFO-1234yf/HFC-32 9 trans HFO-1234ze/HFC-32 HFO-1234yf/HFC-32 10 CO₂ or N₂O trans HFO-1234ze/HFC-32 11 HFO-1234yf/HFC-32 trans HFO-1234ze/HFC-32 12 trans HFO-1234ze/HFC-32 trans HFO-1234ze/HFC-32 13 CO₂ or N₂O trans HFO-1234ze/HFC-134a 14 HFO-1234yf/HFC-32 trans HFO-1234ze/HFC-134a 15 trans HFO-1234ze/HFC-32 trans HFO-1234ze/HFC-134a 16 CO₂ or N₂O trans HFO-1234ze/HFC-125 17 HFO-1234yf/HFC-32 trans HFO-1234ze/HFC-125 18 trans HFO-1234ze/HFC-32 trans HFO-1234ze/HFC-125

In certain embodiments, the second refrigerant may consist essentially of HFO-1234yf. In other embodiments, the second refrigerant may comprise HFO-1234yf and R134a. In yet other embodiments, the second refrigerant may comprise HFO-1234yf and R32, or it may comprise trans HFO-1234ze and HFC-32, or trans HFO-1234ze and HFC-134a or trans HFO-1234ze and HFC-125.

In the embodiment where the second refrigerant consists essentially of HFO-1234yf, the first refrigerant may comprise carbon dioxide (CO₂) or nitrous oxide (N₂O). Alternatively, in the embodiment where the second refrigerant consists essentially of HFO-1234yf, the first refrigerant may comprise HFO-1234yf and HFC-32. In another embodiment, where the second refrigerant consists essentially of HFO-1234yf, the first refrigerant may comprise trans HFO-1234ze and HFC-32.

In the embodiment where the second refrigerant comprises HFO-1234yf and HFC-134a, or when the second refrigerant comprises HFO-1234yf and HFC-32, the first refrigerant may comprise either carbon dioxide or nitrous oxide. Alternatively, in the embodiment where the second refrigerant comprises HFO-1234yf and HFC-134a, or HFO-1234yf and HFC-32, the first refrigerant may comprise HFO-1234yf and HFC-32. In another embodiment, where the second refrigerant comprises HFO-1234yf and HFC-134a, or HFO-1234yf and HFC-32, the first refrigerant may comprise trans HFO-1234ze and HFC-32.

In the particular embodiment where the second refrigerant comprises HFO-1234yf and R134a, and the first refrigerant comprises HFO-1234yf and HFC-32, the second refrigerant may comprise 1-99% HFO-1234yf and 99-1% HFC-134a. In one embodiment, the second refrigerant comprises 1-53.1% HFO-1234yf and 46.9-99% HFC-134a. In particular, the second refrigerant comprises 53% HFO-1234yf and 47% HFC-134a. In one embodiment, the second refrigerant comprises 1-59% HFO-1234yf and 41-99% HFC-134a. In this embodiment, the second refrigerant is non-flammable at 100° C. or 60° C. This composition is non-flammable and has maximum capacity in the range of 40-59% 1234yf and 41-60% 134a. In particular, the second refrigerant may comprise 53% HFO-1234yf and 47% HFC-134a.

In the particular embodiment where the second refrigerant comprises HFO-1234yf and HFC-32, the ranges for these components may be 1-99% HFO-1234yf and 99-1% HFC-32. In a particular embodiment, the second refrigerant may comprise 20-99% HFO-1234yf and 80-99% HFC-32. More particularly, the second refrigerant may comprise 50-99% HFO-1234yf and 50-99% HFC-32, and even more particularly, the second refrigerant may comprise 63% HFO-1234yf and 37% HFC-32. In this embodiment, the second refrigerant may be used as a replacement for R404A. In another embodiment, the second refrigerant may comprise 27.5% HFO-1234yf and 72.5% HFC-32. In this embodiment, the second refrigerant may be used as a replacement for R410A. In any of the embodiments of the foregoing embodiments where the second refrigerant comprises a particular range of HFO-1234yf and HFC-32, the first refrigerant may comprise either CO₂ or N₂O, a blend of HFO-1234yf/HFC-32, or a blend of trans HFO-1234ze/HFC-32.

In the embodiment where the second refrigerant comprises trans HFO-1234ze and HFC-32, the first refrigerant may comprise either carbon dioxide or nitrous oxide. Alternatively, in the embodiment where the second refrigerant comprises trans-HFO-1234ze and HFC-32, the first refrigerant may comprise HFO-1234yf and HFC-32. In another embodiment, where the second refrigerant comprises trans-HFO-1234ze and HFC-32, the first refrigerant may comprise trans HFO-1234ze and HFC-32.

In the particular embodiment where the second refrigerant comprises trans HFO-1234ze and HFC-32, the second refrigerant comprises 1-99% HFO-1234ze and 99-1% HFC-32. The 1234ze may be either trans-1234ze or cis-1234ze. In any of the embodiments of the foregoing embodiments where the second refrigerant comprises a particular range of trans HFO-1234ze and HFC-32, the first refrigerant may comprise the first refrigerant may comprise either CO₂ or N₂O, a blend of HFO-1234yf/HFC-32, or a blend of trans HFO-1234ze/HFC-32.

In the embodiment where the second refrigerant comprises trans HFO-1234ze and HFC-134a, the first refrigerant may comprise either CO₂ or N₂O. Alternatively, in the embodiment where the second refrigerant comprises trans-HFO-1234ze and HFC-134a, the first refrigerant may comprise HFO-1234yf and HFC-32. In another embodiment, where the second refrigerant comprises trans-HFO-1234ze and HFC-134a, the first refrigerant may comprise trans HFO-1234ze and HFC-32.

In the embodiment where the second refrigerant comprises trans HFO-1234ze and HFC-125, the first refrigerant may comprise either carbon dioxide or nitrous oxide. Alternatively, in the embodiment where the second refrigerant comprises trans-HFO-1234ze and HFC-125, the first refrigerant may comprise HFC-32 and HFO-1234yf. In another embodiment, where the second refrigerant comprises trans-HFO-1234ze and HFC-125, the first refrigerant may comprise trans HFO-1234ze and HFC-32.

Various configurations of cascade systems also come within the scope of the present invention. For instance, reference is made to FIG. 2, which shows a cascade system according to the present invention, where elements which correspond to the elements shown in FIG. 1 are indicated with a like reference numeral and a prime (′). The elements in FIG. 2 which correspond to the elements shown in FIG. 1 all operate as described above with respect to FIG. 1. In addition, the cascade system of FIG. 2 includes a secondary heat transfer loop, which includes a secondary fluid chiller 30 and a secondary fluid heat exchanger 32. The secondary fluid heat exchanger is located near a body to be cooled, such as food in a medium temperature display case. The secondary chiller cools a secondary heat transfer fluid. The use of a secondary heat transfer loop in the embodiment of FIG. 2 is advantageous because it limits the amount of refrigerant that must be used and the length of piping through which refrigerant must circulate, while at the same time transferring heat between locations that have to be remote from each other (e.g., remote locations in a large supermarket). Minimization of the amount of refrigerant and length of refrigerant piping reduces refrigerant cost, leakage rates and mitigates risks associated with using refrigerants which are flammable and/or toxic. In addition, or alternatively to the configuration as shown in FIG. 2, a secondary loop could be used to transfer heat form low temp display cases to the LOW temp loop in a configuration similar to that shown in FIG. 2 for the high or mid temp loop. However, the choice of secondary heat transfer fluids would be quit limited because the viscosity of liquids and associated pumping costs increase at low temperatures.

The cascade refrigeration system of FIG. 2 also includes a cascade heat exchanger system disposed between the low temperature refrigeration loop and the medium temperature refrigeration loop. As in the above embodiments, the cascade heat exchanger system has a first inlet 22 a′ and a first outlet 22 b′, wherein the first refrigerant vapor circulates from the first inlet to the first outlet and is condensed in the heat exchanger system to form a first refrigerant liquid, thereby rejecting heat. The cascade heat exchanger system also includes a second inlet 22 c′ and a second outlet 22 d′, wherein a second refrigerant liquid circulates from the second inlet to the second outlet and absorbs the heat rejected by the first refrigerant and forms a second refrigerant vapor, as will be explained below. Thus, in the embodiment of FIG. 2, the heat rejected by the first refrigerant is directly absorbed by the second refrigerant.

Referring specifically to FIG. 2, a secondary heat transfer fluid enters the secondary chiller at a first inlet 30 a and exits the secondary chiller at a first outlet 30 b. The secondary heat transfer fluid may comprise ethylene glycol, propylene glycol, carbon dioxide, water brine or any of several other fluids or slurries known to the art. In some embodiments, the secondary heat transfer fluid may undergo a phase change. In addition the secondary chiller includes a second inlet 30 c and a second outlet 30 d. The second refrigerant enters the secondary fluid chiller through second inlet 30 c and evaporates, thus causing the heat transfer fluid in the chiller to be cooled. The cooled heat transfer fluid exits the chiller 30 through first outlet 30 b and circulates to a secondary fluid heat exchanger 32 located near a body to be cooled. This body to be cooled may be food items inside a refrigerated display case in a supermarket. The heat transfer fluid is warmed by this body and returns to the secondary fluid chiller to be cooled again by the evaporation of the second refrigerant, which also circulates through the secondary fluid chiller. A liquid pump (not shown) pumps the heat transfer fluid from the secondary fluid heat exchanger back to the secondary fluid chiller. This warmed heat transfer fluid causes the second refrigerant to evaporate in the secondary fluid chiller. A separate expansion device (not shown) may be disposed in the inlet line entering cascade heat exchanger 22′ and the inlet line entering secondary fluid chiller 30 in order to control the pressure and flow rate through the cascade heat exchanger and the secondary fluid chiller, respectively. Although cascade heat exchanger 22′ and secondary fluid chiller 30 are shown connected in parallel, they may alternatively be connected in series without departing from the scope of the present invention.

A portion of the reduced pressure and temperature second refrigerant liquid which exits condenser 26′ enters the cascade heat exchanger 22′ at inlet 22 c′. In cascade heat exchanger 22′, as in the first embodiment of FIG. 1, the first refrigerant is condensed, and the second refrigerant evaporates and exits from the heat exchanger 22′ at outlet 22 d′. The second refrigerant which exits secondary fluid chiller 30 at second outlet 30 d merges with the second refrigerant from outlet 22 d′ of the cascade heat exchanger and circulates to second compressor 24′. The cycle through medium temperature loop 14′ and low temperature loop 12′ are otherwise the same as discussed above with respect to FIG. 1.

Another embodiment of the cascade refrigeration system of the present invention is shown in FIG. 3. In the embodiment of FIG. 3, elements which correspond to the elements shown in FIG. 1 are indicated with a like reference numeral and a double prime (″). The elements in FIG. 3 which correspond to the elements shown in FIG. 1 all operate as described above with respect to FIG. 1. The system of FIG. 3 includes a secondary heat transfer loop, shown generally at 40, which includes two cascade heat exchangers instead of one cascade heat exchanger as shown in the embodiments of FIGS. 1 and 2. As in the embodiment of FIG. 2, the use of a secondary heat transfer loop in the embodiment of FIG. 3 is advantageous because it limits the amount of refrigerant that must be used and the length of piping through which refrigerant must circulate, while at the same time transferring heat between locations that have to be remote from each other.

The embodiment of FIG. 3 includes a cascade heat exchanger system which includes two cascade heat exchangers connected to each other through a secondary heat transfer loop. The cascade heat exchanger system in FIG. 3 has a first inlet 42 a and a first outlet 42 b, wherein the first refrigerant vapor circulates from the first inlet to the first outlet and is condensed in the cascade heat exchanger system to form a first refrigerant liquid, thereby rejecting heat. The cascade heat exchanger system also includes a second inlet 44 c and a second outlet 44 d, wherein a second refrigerant liquid circulates from the second inlet to the second outlet and indirectly absorbs the heat rejected by the first refrigerant and forms a second refrigerant vapor. In the embodiment of FIG. 3, the second refrigerant liquid indirectly absorbs the heat rejected by the first refrigerant through the secondary heat transfer fluid, that is to say, the first refrigerant rejects heat to the heat transfer fluid, and the heat transfer fluid circulates to the second cascade heat exchanger 44 where it transfers the heat from the first refrigerant to the second refrigerant, as will be described below. This heat is rejected to ambient.

Referring to FIG. 3, cascade refrigeration system 10″ includes a first cascade heat exchanger 42 in low temperature loop 12″, having a first inlet 42 a and a first outlet 42 b, and a second inlet 42 c and a second outlet 42 d. The medium temperature loop 14″ includes a second cascade heat exchanger 44, having a first inlet 44 a and a first outlet 44 b, and a second inlet 44 c and a second outlet 44 d. Compressed first refrigerant vapor circulates from the outlet of the first compressor 20 b″ as shown in FIG. 3 to the first inlet 42 a of the first heat exchanger 42. As in the embodiment shown in FIG. 1, this compressed refrigerant vapor is condensed in the first cascade heat exchanger to form a first refrigerant liquid, thereby rejecting heat. The first refrigerant liquid then circulates to the first outlet 42 b of the first cascade heat exchanger. A heat transfer fluid circulates in the secondary heat transfer loop between the first cascade heat exchanger and a second cascade heat exchanger 44, which is also part of the medium temperature loop 14″. Specifically, the heat transfer fluid enters first heat exchanger 42 through a second inlet 42 c and exits the first heat exchanger through a second outlet 42 d. This heat transfer fluid absorbs the heat rejected by the condensing first refrigerant that enters that heat exchanger through inlet 42 a, and is warmed. The warmed heat transfer fluid exits the first heat exchanger through second outlet 42 d and circulates to second heat exchanger 44. The heat transfer fluid is cooled in the second heat exchanger by rejecting heat to the second refrigerant, which enters the second heat exchanger at a second inlet 44 c, and exits the second heat exchanger at a second outlet 44 d. The second refrigerant evaporates in the second cascade heat exchanger since it is warmed by the heat transfer fluid, and forms a second refrigerant vapor. Cooled heat transfer fluid exits the first outlet 44 b of the second heat exchanger. The cycle through the low temperature loop 12″ and the medium temperature loop 14″ are otherwise the same as discussed above with respect to FIG. 1, except that in this embodiment, the first and/or second refrigerant may be, but need not necessarily be, a fluoroolefin.

A further embodiment of the cascade refrigeration system of the present invention is shown in FIG. 4. In the embodiment of FIG. 4, elements which correspond to the elements shown in FIG. 1 are indicated with a like reference numeral and a triple prime (′″). The elements in FIG. 4 which correspond to the elements shown in FIG. 1 all operate as described above with respect to FIG. 1. The system of FIG. 4 includes two low temperature loops, Loop 12A, which is similar to the low temperature loop 12 of FIG. 1, and Loop 12B. One of the two low temperature loops, e.g., loop 12B, provides refrigeration at a temperature which is different from, for example, intermediate to, the temperature at which refrigeration is provided by the other low temperature loop and by the medium temperature loop. The advantage of such a system is that the refrigerant in the low temperature loop can be used to cool two different bodies, such as two separate freezer display cases, at two different temperatures.

In the embodiment of FIG. 4, a cascade heat exchanger system is disposed between the two loops. The cascade heat exchanger system has a first inlet 22 a′″ and a second inlet 22 b′″, and a first outlet 52 wherein the first refrigerant vapor circulates from the first and second inlets to the first outlet and is condensed in the heat exchanger system to form a first refrigerant liquid, thereby rejecting heat. The cascade heat exchanger system also includes a third inlet 22 c′″ and a second outlet 22 d′″, wherein a second refrigerant liquid circulates from the third inlet to the second outlet and absorbs the heat rejected by the first refrigerant and forms a second refrigerant vapor. Thus, in the embodiment of FIG. 4, the heat rejected by the first refrigerant is directly absorbed by the second refrigerant and this is rejected to ambient.

It should be noted that it is within the scope of the present invention that the embodiment of FIG. 4 encompasses all cascade heat exchanger systems that transfer heat in the above described manner.

In the system of the embodiment of FIG. 4, the flow of the first refrigerant liquid is split as or after it exits the cascade heat exchanger 22′″ at 52. One portion circulates through one low temperature loop 12A, and another portion circulates through the other low temperature loop 12B. The portion of the first refrigerant that circulates through loop 12B enters an additional expansion device 54 at inlet 54 a, and the pressure and temperature of this portion of the first refrigerant liquid is reduced. This reduced pressure and temperature liquid refrigerant then circulates through outlet 54 b of the additional expansion device, and circulates to an additional evaporator 56. It should be noted that this liquid may be partially vaporized during this expansion. The additional evaporator 56 includes an inlet 56 a and an outlet 56 b. The refrigerant liquid from the additional expansion device enters the evaporator through evaporator inlet 56 a and is evaporated in the evaporator to form a refrigerant vapor, thereby producing cooling, and circulates to outlet 56 b. Low temperature loop 12B also includes an additional compressor 58 having an inlet 58 a and an outlet 58 b. The first refrigerant vapor from additional evaporator 56 circulates to inlet 58 a of the additional compressor 58 and is compressed, thereby increasing the pressure and the temperature of the first refrigerant vapor, and the compressed first refrigerant vapor circulates to outlet 58 b of the additional compressor and to the inlet 22 b′″ of the cascade heat exchanger 22′″. The cycle through the other low temperature loop 12A and the medium temperature loop 14′″ are otherwise the same as discussed above with respect to FIG. 1. In particular, low temperature loop 12A also includes an evaporator 18′″, which could be housed inside a freezer display case, and additional evaporator 56 could be housed inside a freezer display case. This system thereby could provide cooling to two separate freezer display cases.

Further in accordance with the present invention, there is provided a method of exchanging heat between at least two refrigeration loops, comprising: (a) absorbing heat from a body to be cooled in a first refrigeration loop and rejecting this heat to a second refrigeration loop; and (b) absorbing the heat from the first refrigeration loop in the second refrigeration loop and rejecting this heat to ambient. The refrigerant in either loop, i.e., the loop in which heat is absorbed or the loop in which heat is rejected, or both, may comprise a fluoroolefin. The heat from the first refrigeration loop may be absorbed directly in the second refrigeration loop, such as in the embodiments of FIGS. 1, 2 and 4, or it may be directly absorbed in the second refrigeration loop, such as in the embodiment of FIG. 3.

EXAMPLES Example 1 Cooling Performance for Upper Temperature Circuit of a Cascade System

Table 5 shows the performance of some exemplary compositions as compared to HFC-134a. In Table 5, Evap Pres is evaporator pressure, Cond Pres is condenser pressure, Comp Disch T is compressor discharge temperature, COP is coefficient of performance (analogous to energy efficiency), CAP is capacity, Avg. Temp. glide is the average of the temperature glide in the evaporator and condenser, and GWP is global warming potential. The data are based on the following conditions.

Evaporator temperature −10° C. Condenser temperature 40.0° C. Subcool amount 6° C. Return gas temperature 10° C. Compressor efficiency is 70%

Note that the evaporator superheat enthalpy is not included in cooling capacity and energy efficiency determinations.

TABLE 5 Compr CAP COP Avg. Evap Cond Disch relative relative Temp. Press Press Temp CAP to 134a to 134a Glide, Composition (kPa) (kPa) (° C.) (Kw) (%) COP (%) ° C. GWP* HFC-134a 200.6 1016.5 81.4 2.231 2.742 0 1430 HFO-1234yf 220.5 1015.6 68.3 2.113 94.7 2.580 94.1 0 4 HFO-1234yf/HFC-134a 224.8 1097.0 78.1 2.371 106.3 2.685 97.9 0.05 1145 (20/80 wt %) HFO-1234yf/HFC-134a 245.3 1149.3 74.7 2.470 110.7 2.653 96.8 0.25 848 (40/60 wt %) HFO-1234yf/HFC-134a 252.1 1160.2 72.8 2.487 111.5 2.640 96.3 0.10 674 (53/47 wt %) HFO-1234yf/HFC-134a 252.7 1156.7 72.0 2.475 110.9 2.635 96.1 0.11 574 (60/40 wt %) HFO-1234yf/HFC-134a 243.4 1112.0 70.0 2.357 105.6 2.618 95.5 0.80 138 (80/20 wt %) HFO-1234ze/HFC-134a 193.9 981.3 80.2 2.150 96 2.741 100 0.17 1145 (20/80 wt %) HFO-1234ze/HFC-134a 184.6 937.6 79.1 2.052 92 2.744 100 0.40 860 (40/60 wt %) HFO-1234ze/HFC-134a 189.3 912.9 78.6 1.996 89 2.746 100 0.51 718 (50/50 wt %) HFO-1234ze/HFC-134a 173.4 886.4 78.1 1.937 87 2.749 100 0.59 576 (60/40 wt %) HFO-1234ze/HFC-134a 160.7 828.6 77.2 1.808 81 2.756 101 0.53 293 (80/20 wt %) HFO-1234ze/HFC-125 156.7 814.4 76.3 1.769 79 2.756 101 1.61 184 (95/5 wt %) HFO-1234ze/HFC-125 166.6 864.4 76.4 1.869 84 2.746 100 2.96 355 (90/10 wt %) HFO-1234ze/HFC-125 176.9 915.0 76.4 1.968 88 2.735 100 4.08 530 (85/15 wt %) HFO-1234ze/HFC-125 187.7 966.1 76.4 2.067 93 2.718 99 4.99 705 (80/20 wt %) *The GWP value for HFC-134a is taken from the “Climate Change 2007 - IPCC (Intergovernmental Panel on Climate Change) Fourth Assessment Report on Climate Change”, from the section entitled “Working Group 1 Report: “The Physical Science Basis”, Chapter 2, pp. 212-213, Table 2.14. The value for HFO-1234yf was published in Papadimitriou et al., Physical Chemistry Chemical Physics, 2007, vol. 9, pp. 1-13. Specifically, the 100 year time horizon GWP values are used. The GWP values for the compositions containing HFC-134a and HFO-1234yf are calculated as weighted averages of the individual component GWP values.

The data in Table 5 indicate that the 1234yf/134a compositions are a close match to 134a, in terms of COP, capacity, pressures and temperatures in the system, with lower GWP values. In addition, all the compositions have low temperature glide and a specific composition could be selected based on regulatory requirements for GWP, which have not at this time been determined. The composition containing 53 wt % HFO-1234yf and 47 wt % HFC-134a has the particular benefit of providing a low GWP and a peak in the cooling capacity. This is shown graphically in FIG. 5.

Example 2 Flammability of HFO-1234vf/HFC-134a Mixtures

Flammable compositions may be identified by testing under ASTM (American Society of Testing and Materials) E681-2004, with an electronic ignition source. Such tests of flammability were conducted on compositions containing HFO-1234yf and HFC-134a at 101 kPa (14.7 psia), 50 percent relative humidity, and about 23° C. (room temperature), 60° C. and 100° C. at various concentrations in air in order to determine if flammable and if so, to find the lower flammability limit (LFL) and the upper flammability limit (UFL). The results are given in Table 6.

TABLE 6 % HFO- % HFC- Room Temp. 60° C. 100° C. 1234yf 134a LFL UFL LFL UFL LFL UFL 50.00 50.00 non-flammable non-flammable non-flammable 52.50 47.50 non-flammable non-flammable non-flammable 53.10 46.9 non-flammable non-flammable non-flammable 53.75 46.25 non-flammable non-flammable 10.0% (single point) 55.00 45.00 non-flammable non-flammable 9.0% 10.5% 57.50 42.50 non-flammable non-flammable 8.0% 12.0% 59.00 41.0 non-flammable non-flammable not tested 60.00 40.00 non-flammable 10.0% (single point) not tested 60.63 39.37 non-flammable 10.0% 11.0% not tested 61.25 38.75 non-flammable 10.0% 11.0% not tested 62.50 37.50 non-flammable 8.75% 10.75% not tested 65.00 35.00 non-flammable 8.0% 12.0% not tested 66.25 33.75 non-flammable not tested not tested 67.50 32.50 10.0% (single point) not tested not tested 70.00 30.00 9.0% 11.0% not tested not tested

At room temperature conditions (about 23° C.), compositions with 66.25 weight percent or less HFO-1234yf in HFC-134a would be considered non-flammable. At 60° C., compositions with 60.00 weight percent or less HFO-1234yf in HFC-134a would be considered non-flammable. At 100° C., compositions containing 53.10 weight percent or less HFO-1234yf in HFC-134a would be considered non-flammable.

Example 3 Cooling Performance for Low Temperature Circuit of a Cascade System

Table 7 shows the performance of certain compositions as compared to CO₂, R404A (ASHRAE designation for a mixture containing HFC-125, HFC-134a, and HFC-143a), R410A (ASHRAE designation for a mixture containing HFC-32 and HFC-125) and HFC-32. In Table 7, Evap Pres is evaporator pressure, Cond Pres is condenser pressure, Comp Disch T is compressor discharge temperature, COP is coefficient of performance (analogous to energy efficiency), CAP is capacity, Avg. Temp. glide is the average of the temperature glide in the evaporator and condenser, and GWP is global warming potential. The data are based on the following conditions.

Evaporator temperature −35° C. Condenser temperature −6° C. Subcool amount 0° C. Return gas temperature −25° C. Compressor efficiency is 70%

Note that the evaporator superheat enthalpy is not included in cooling capacity and energy efficiency determinations.

TABLE 7 Compr Evap Cond Disch Avg. Press Press Temp CAP Temp. Composition (kPa) (kPa) (° C.) (kW) COP Glide, ° C. GWP* CO₂ 1204.7 2960.8 57.3 12.132 4.229 0 1 R404A 168.3 449.4 20.0 2.175 4.791 0.5 3922 HFO-1234yf/HFC-32 163.6 503.5 31.5 2.271 4.875 6.7 252 (63/37 wt %) R410A 220.1 654.1 38.3 2.966 4.836 0.1 2088 HFO-1234yf/HFC-32 213.6 635.4 46.4 2.934 4.865 0.8 490 (27.5/72.5 wt %) HFO-1234yf/HFC-32 185.6 561.8 36.9 2.547 4.853 4.3 340 (50/50 wt %) HFO-1234yf/HFC-32 200.2 599.6 41.0 2.739 4.851 2.5 407 (40/60 wt %) HFO-1234yf/HFC-32 218.2 649.8 50.2 3.015 4.852 0.3 541 (20/80 wt %) HFC-32 221.0 666.3 60.8 3.126 4.833 0 675 HFO-1234ze/HFC-32 60.8 220.1 28.6 0.982 4.947 4.7 73 (90/10 wt %) HFO-1234ze/HFC-32 74.7 266.2 33.2 1.201 4.958 7.5 140 (80/20 wt %) HFO-1234ze/HFC-32 89.1 311.4 37.4 1.419 4.968 9.1 207 (70/30 wt %) HFO-1234ze/HFC-32 104.1 356.1 41.4 1.637 4.958 9.8 274 (60/40 wt %) HFO-1234ze/HFC-32 119.6 400.9 45.2 1.855 4.944 9.8 341 (50/50 wt %) HFO-1234ze/HFC-32 135.9 446.6 48.8 2.074 4.927 9.2 407 (40/60 wt %) HFO-1234ze/HFC-32 144.1 469.9 50.6 2.185 4.907 8.6 441 (35/65 wt %) HFO-1234ze/HFC-32 153.0 493.8 52.4 2.298 4.892 8.0 474 (30/70 wt %) HFO-1234ze/HFC-32 162.1 518.4 54.1 2.413 4.875 7.2 508 (25/75 wt %) HFO-1234ze/HFC-32 171.7 543.9 55.7 2.532 4.858 6.2 541 (20/80 wt %) HFO-1234ze/HFC-32 193.1 599.4 58.7 2.793 4.830 3.7 608 (10/90 wt %) *The GWP value for HFCs are taken from the “Climate Change 2007 - IPCC (Intergovernmental Panel on Climate Change) Fourth Assessment Report on Climate Change”, from the section entitled “Working Group 1 Report: “The Physical Science Basis”, Chapter 2, pp. 212-213, Table 2.14. The value for HFO-1234yf was published in Papadimitriou et al., Physical Chemistry Chemical Physics, 2007, vol. 9, pp. 1-13. Specifically, the 100 year time horizon GWP values are used. The GWP values for the compositions containing more than one component are calculated as weighted averages of the individual component GWP values.

The composition containing 63 wt % HFO-1234yf and 37 wt % HFC-32 actually shows improved COP and capacity relative to R404A and also has significantly lower GWP. The composition containing 27.5 wt % HFO-1234yf and 72.5 wt % HFC-32 matches the COP and capacity of R410A, has very low temperature glide indicating azeotrope-like behavior and also has significantly lower GWP.

Note that all compositions comprising mixtures of HFO-1234yf and HFC-32 have improved COP (energy efficiency) as compared to CO₂.

Example 4 Total Equivalent Warming Impact

The total equivalent warming impact (TEWI) is determined for systems as disclosed herein in comparison to conventional uncoupled supermarket refrigeration systems as well as conventional cascade systems. The TEWI takes into consideration the effects of the energy efficiency of the system, the contribution due to the energy source used to provide the electrical power to the equipment, and the amount of refrigerant charged to the system as well as the rate of leakage to quantify a more complete environmental impact of use of different refrigerants.

This Example uses a conventional European direct expansion (DX) supermarket refrigeration system, traditionally using R404A in both medium temperature (MT) and low temperature (LT) refrigeration systems, as the base case for comparison. Certain assumptions were made based on a typical European supermarket system are shown in Table 8. Additionally, the expected equipment life was assumed to be 15 years and the CO₂ emitted from electricity generation was estimated to be 0.616 kg CO₂/kw-hr.

TABLE 8 Variable MT cycle LT cycle Operating power (kw) 75 20 Fractional run time (%) 55 85 Refrigerant charge (kg) 200 100 Average refrigerant emission rate* 15 15 (% of charge per year) End-of-life recovery of refrigerant (%) 80 80 *Includes fugitive and accidental releases, independent of refrigerant choice.

Table 9 provides the conditions for which the system performance (COP, or coefficient of performance, a measure of energy efficiency) was estimated. In Table 9, temp is temperature, evap is evaporator, cond is condenser, and comp is compressor.

TABLE 9 Cycle Uncoupled Cascade MT evap temp = −10° C. evap temp = −10° C. cond temp = 40° C. cond temp = 40° C. return gas temp = +10° C. return gas temp = +10° C. subcool temp = 6° C. subcool temp = 6° C. comp efficiency = 0.70 comp efficiency = 0.70 LT evap temp = −35° C. evap temp = −35° C. cond temp = 40° C. cond temp = −6° C. return gas temp = −15° C. return gas temp = −15° C. subcool temp = 6° C. subcool temp = 0° C. comp efficiency = 0.70 comp efficiency = 0.70

Table 10 lists several different embodiments of the present invention as compared to conventional uncoupled and cascade systems for which the determinations of TEWI are made, as well as the estimated COP values as calculated based on the conditions listed above in Table 9.

TABLE 10 System MT refrigerant MT LT refrigerant LT Cascade/ designation (GWP) COP (GWP) COP uncoupled 0 R404A (3922) 2.62 R404A (3922) 1.36 Uncoupled 1 HFC-134a (1430) 2.88 R404A (3922) 1.36 Uncoupled 1a HFC-134a (1430) 2.88 R404A (3922) 4.75 Cascade 2 R404A (3922) 2.62 CO₂ (1) 4.20 Cascade 3 HFO-1234yf/HFC- 2.89 CO₂ (1) 4.20 Cascade 134a, 53/47 wt % (674) 4 HFO-1234yf (4) 2.80 CO₂ (1) 4.20 Cascade 5a Supercritical CO₂ (1) 2.31(*) CO₂ (1) 4.20 Cascade (northern EU) 5b Supercritical CO₂ (1) 2.04(*) CO₂ (1) 4.20 Cascade (southern EU) (*)These values for COP were estimated to match published data on energy consumption relative to a system using R404A in both MT and LT loops. (Sienel, T.; Finckh, O., “CO₂-DX Systems for Medium- and Low-Temperature Refrigeration in Supermarket Applications”, International Congress of Refrigeration, 2007, Beijing, China).

The TEWI value includes an indirect contribution, which incorporates energy source and usage, and a direct contribution due to the emissions of refrigerant with a given GWP from a system. Table 11 lists the indirect and direct contributions and the TEWI value calculated for the different systems described above, in terms of equivalent CO₂ emissions over equipment life (in million kg) in order from greatest to least environmental impact.

TABLE 11 From From From energy From energy refrigerant refrigerant System consumption, consumption, Indirect emissions, emissions, Direct designation MT loop LT loop contribution MT loop LT loop contribution TEWI 0 3.34 1.38 4.72 1.92 0.96 2.88 7.60 1 3.04 1.38 4.42 0.70 0.96 1.66 6.08 2 3.34 0.45 3.79 1.92 0 1.92 5.71 1a 3.04 0.39 3.43 0.70 0.96 1.66 5.09 5b 4.27 0.45 4.72 0 0 0 4.72 5a 3.81 0.45 4.26 0 0 0 4.26 3 3.04 0.45 3.57 0.33 0 0.33 3.81 4 3.12 0.45 3.57 0 0 0 3.57

The results in Table 11 demonstrate that the use of HFO-based refrigerants (e.g. in the medium temperature loop of cascade refrigeration systems 3 and 4) can lead to lower TEWI values than those for uncoupled or cascade refrigeration systems using refrigerants known to the prior art. 

1. A cascade refrigeration system having at least two refrigeration loops, each circulating a refrigerant therethrough, comprising: (a) a first expansion device for reducing the pressure and temperature of a first refrigerant liquid; (b) an evaporator having an inlet and an outlet, wherein the first refrigerant liquid from the first expansion device enters the evaporator through the evaporator inlet and is evaporated in the evaporator to form a first refrigerant vapor, thereby producing cooling, and circulates to the outlet; (c) a first compressor having an inlet and an outlet, wherein the first refrigerant vapor from the evaporator circulates to the inlet of the first compressor and is compressed, thereby increasing the pressure and the temperature of the first refrigerant vapor, and the compressed first refrigerant vapor circulates to the outlet of the first compressor; (d) a cascade heat exchanger system having: (i) a first inlet and a first outlet, wherein the first refrigerant vapor circulates from the first inlet to the first outlet and is condensed in the heat exchanger system to form a first refrigerant liquid, thereby rejecting heat, and (ii) a second inlet and a second outlet, wherein a second refrigerant liquid circulates from the second inlet to the second outlet and absorbs the heat rejected by the first refrigerant and forms a second refrigerant vapor; (e) a second compressor having an inlet and an outlet, wherein the second refrigerant vapor from the cascade heat exchanger system is drawn into the compressor and is compressed, thereby increasing the pressure and temperature of the second refrigerant vapor; (f) a condenser having an inlet and an outlet for circulating the second refrigerant vapor therethrough and for condensing the second refrigerant vapor from the compressor to form a second refrigerant liquid, wherein the second refrigerant liquid exits the condenser through the outlet; and (g) a second expansion device for reducing the pressure and temperature of the second refrigerant liquid exiting the condenser and entering the second inlet of the cascade heat exchanger system; wherein at least one of the first and the second refrigerant comprises a fluoroolefin.
 2. The system of claim 1, wherein the second refrigerant comprises a fluorolefin selected from the group consisting of HFO-1234yf, trans-1234ze and E-1234ze.
 3. The system of claim 1, wherein the second refrigerant consists essentially of HFO-1234yf.
 4. The system of claim 2, wherein the second refrigerant also comprises R134a.
 5. The system of claim 2, wherein the second refrigerant also comprises HFC-32.
 6. The system of claim 3, wherein the first refrigerant comprises a composition selected from the group consisting of carbon dioxide and nitrous oxide.
 7. The system of claim 3, wherein the first refrigerant comprises HFO-1234yf and HFC-32.
 8. The system of claim 4, wherein the first refrigerant comprises a composition selected from the group consisting of carbon dioxide and nitrous oxide.
 9. The system of claim 4, wherein the first refrigerant comprises HFO-1234yf and HFC-32.
 10. The system of claim 5, wherein the second refrigerant comprises HFO-1234yf.
 11. The system of claim 5, wherein the second refrigerant comprises trans-1234ze.
 12. The system of claim 5 wherein the first refrigerant comprises carbon dioxide or nitrous oxide.
 13. The system of claim 5, wherein the first refrigerant comprises HFO-1234yf and HFC-32.
 14. A cascade refrigeration system having at least two refrigeration loops, each circulating a refrigerant therethrough, comprising: a first refrigeration loop, including: (a) a first expansion device for reducing the pressure and temperature of a first refrigerant liquid; (b) an evaporator having an inlet and an outlet, wherein the first refrigerant liquid from the first expansion device enters the evaporator through the evaporator inlet and is evaporated in the evaporator to form a first refrigerant vapor, thereby producing cooling, and circulates to the outlet; (c) a first compressor having an inlet and an outlet, wherein the first refrigerant vapor from the evaporator circulates to the inlet of the first compressor and is compressed, thereby increasing the pressure and the temperature of the first refrigerant vapor, and the compressed first refrigerant vapor circulates to the outlet of the first compressor; (d) a cascade heat exchanger system comprising: (i) a first cascade heat exchanger having: (A) a first inlet and a first outlet, wherein the first refrigerant vapor from the evaporator circulates from the first inlet to the first outlet and is condensed in the first heat exchanger to form a first refrigerant liquid, thereby rejecting heat, and (B) a second inlet and a second outlet, wherein a heat transfer fluid circulates from the second inlet to the second outlet, wherein the heat rejected by the first refrigerant vapor as it is condensed is absorbed by the heat transfer fluid, (ii) a second cascade heat exchanger having: (A) a first inlet and a first outlet, wherein the heat transfer fluid from the first cascade heat exchanger circulates from the first inlet to the first outlet and rejects the heat absorbed in the first cascade heat exchanger, and (B) a second inlet and a second outlet, wherein a second refrigerant liquid circulates from the second inlet to the second outlet and absorbs the heat rejected by the heat transfer fluid and forms a second refrigerant vapor; (e) a second compressor having an inlet and an outlet, wherein the second refrigerant vapor from the second cascade heat exchanger is drawn into the compressor and is compressed, thereby increasing the pressure and temperature of the second refrigerant vapor; (f) a condenser having an inlet and an outlet for circulating the second refrigerant vapor therethrough and for condensing the second refrigerant vapor from the compressor to form a second refrigerant liquid, wherein the second refrigerant liquid exits the condenser through the outlet; and (g) a second expansion device for reducing the pressure and temperature of the second refrigerant liquid exiting the condenser and entering the second inlet of the second cascade heat exchanger.
 15. A method of exchanging heat between at least two refrigeration loops, comprising: (a) absorbing heat from a body to be cooled in a first refrigeration loop and rejecting this heat to a second refrigeration loop; and (b) absorbing the heat from the first refrigeration loop in the second refrigeration loop and rejecting this heat to ambient, wherein the refrigerant in at least one of the refrigeration loops comprises a fluoroolefin. 